diff --git a/dvc/command/gc.py b/dvc/command/gc.py
--- a/dvc/command/gc.py
+++ b/dvc/command/gc.py
@@ -21,7 +21,7 @@ def run(self):
 
         msg = "This will remove all cache except items used in "
 
-        msg += "the working tree"
+        msg += "the workspace"
         if self.args.all_commits:
             msg += " and all git commits"
         elif self.args.all_branches and self.args.all_tags:
@@ -77,7 +77,7 @@ def add_parser(subparsers, parent_parser):
         "--workspace",
         action="store_true",
         default=False,
-        help="Keep data files used in the current workspace (working tree).",
+        help="Keep data files used in the current workspace.",
     )
     gc_parser.add_argument(
         "-a",
diff --git a/dvc/repo/brancher.py b/dvc/repo/brancher.py
--- a/dvc/repo/brancher.py
+++ b/dvc/repo/brancher.py
@@ -18,7 +18,7 @@ def brancher(  # noqa: E302
         str: the display name for the currently selected tree, it could be:
             - a git revision identifier
             - empty string it there is no branches to iterate over
-            - "Working Tree" if there are uncommitted changes in the SCM repo
+            - "workspace" if there are uncommitted changes in the SCM repo
     """
     if not any([revs, all_branches, all_tags, all_commits]):
         yield ""
@@ -30,10 +30,10 @@ def brancher(  # noqa: E302
     scm = self.scm
 
     self.tree = WorkingTree(self.root_dir)
-    yield "working tree"
+    yield "workspace"
 
-    if revs and "working tree" in revs:
-        revs.remove("working tree")
+    if revs and "workspace" in revs:
+        revs.remove("workspace")
 
     if all_commits:
         revs = scm.list_all_commits()
diff --git a/dvc/repo/diff.py b/dvc/repo/diff.py
--- a/dvc/repo/diff.py
+++ b/dvc/repo/diff.py
@@ -7,7 +7,7 @@
 @locked
 def diff(self, a_rev="HEAD", b_rev=None):
     """
-    By default, it compares the working tree with the last commit's tree.
+    By default, it compares the workspace with the last commit's tree.
 
     This implementation differs from `git diff` since DVC doesn't have
     the concept of `index`, but it keeps the same interface, thus,
diff --git a/dvc/repo/metrics/show.py b/dvc/repo/metrics/show.py
--- a/dvc/repo/metrics/show.py
+++ b/dvc/repo/metrics/show.py
@@ -104,13 +104,13 @@ def show(
     if not res:
         raise NoMetricsError()
 
-    # Hide working tree metrics if they are the same as in the active branch
+    # Hide workspace metrics if they are the same as in the active branch
     try:
         active_branch = repo.scm.active_branch()
     except TypeError:
         pass  # Detached head
     else:
-        if res.get("working tree") == res.get(active_branch):
-            res.pop("working tree", None)
+        if res.get("workspace") == res.get(active_branch):
+            res.pop("workspace", None)
 
     return res
diff --git a/dvc/repo/params/show.py b/dvc/repo/params/show.py
--- a/dvc/repo/params/show.py
+++ b/dvc/repo/params/show.py
@@ -58,13 +58,13 @@ def show(repo, revs=None):
     if not res:
         raise NoParamsError("no parameter configs files in this repository")
 
-    # Hide working tree params if they are the same as in the active branch
+    # Hide workspace params if they are the same as in the active branch
     try:
         active_branch = repo.scm.active_branch()
     except TypeError:
         pass  # Detached head
     else:
-        if res.get("working tree") == res.get(active_branch):
-            res.pop("working tree", None)
+        if res.get("workspace") == res.get(active_branch):
+            res.pop("workspace", None)
 
     return res
diff --git a/dvc/repo/plots/data.py b/dvc/repo/plots/data.py
--- a/dvc/repo/plots/data.py
+++ b/dvc/repo/plots/data.py
@@ -258,7 +258,7 @@ def _load_from_revisions(repo, datafile, revisions):
     exceptions = []
 
     for rev in repo.brancher(revs=revisions):
-        if rev == "working tree" and rev not in revisions:
+        if rev == "workspace" and rev not in revisions:
             continue
 
         try:
diff --git a/dvc/repo/plots/diff.py b/dvc/repo/plots/diff.py
--- a/dvc/repo/plots/diff.py
+++ b/dvc/repo/plots/diff.py
@@ -3,7 +3,7 @@ def _revisions(revs, is_dirty):
     if len(revisions) <= 1:
         if len(revisions) == 0 and is_dirty:
             revisions.append("HEAD")
-        revisions.append("working tree")
+        revisions.append("workspace")
     return revisions
 
 
diff --git a/dvc/repo/plots/show.py b/dvc/repo/plots/show.py
--- a/dvc/repo/plots/show.py
+++ b/dvc/repo/plots/show.py
@@ -106,7 +106,7 @@ def _infer_y_field(rev_data_points, x_field):
 
 def _show(repo, datafile=None, revs=None, props=None):
     if revs is None:
-        revs = ["working tree"]
+        revs = ["workspace"]
 
     if not datafile and not props.get("template"):
         raise NoDataOrTemplateProvided()

diff --git a/tests/func/metrics/test_show.py b/tests/func/metrics/test_show.py
--- a/tests/func/metrics/test_show.py
+++ b/tests/func/metrics/test_show.py
@@ -56,7 +56,7 @@ def test_show_branch(tmp_dir, scm, dvc, run_copy_metrics):
         tmp_dir.scm_gen("metrics.yaml", "foo: 2", commit="branch")
 
     assert dvc.metrics.show(revs=["branch"]) == {
-        "working tree": {"metrics.yaml": {"foo": 1}},
+        "workspace": {"metrics.yaml": {"foo": 1}},
         "branch": {"metrics.yaml": {"foo": 2}},
     }
 
@@ -90,6 +90,6 @@ def test_show_subrepo_with_preexisting_tags(tmp_dir, scm):
 
     expected_path = os.path.join("subdir", "metrics.yaml")
     assert dvc.metrics.show(all_tags=True) == {
-        "working tree": {expected_path: {"foo": 1}},
+        "workspace": {expected_path: {"foo": 1}},
         "v1": {expected_path: {"foo": 1}},
     }
diff --git a/tests/func/params/test_show.py b/tests/func/params/test_show.py
--- a/tests/func/params/test_show.py
+++ b/tests/func/params/test_show.py
@@ -49,7 +49,7 @@ def test_show_branch(tmp_dir, scm, dvc):
         tmp_dir.scm_gen("params.yaml", "foo: baz", commit="branch")
 
     assert dvc.params.show(revs=["branch"]) == {
-        "working tree": {"params.yaml": {"foo": "bar"}},
+        "workspace": {"params.yaml": {"foo": "bar"}},
         "branch": {"params.yaml": {"foo": "baz"}},
     }
 
diff --git a/tests/func/plots/test_diff.py b/tests/func/plots/test_diff.py
--- a/tests/func/plots/test_diff.py
+++ b/tests/func/plots/test_diff.py
@@ -32,8 +32,8 @@ def test_diff_dirty(tmp_dir, scm, dvc, run_copy_metrics):
 
     plot_content = json.loads(plot_string)
     assert plot_content["data"]["values"] == [
-        {"y": 5, PlotData.INDEX_FIELD: 0, "rev": "working tree"},
-        {"y": 6, PlotData.INDEX_FIELD: 1, "rev": "working tree"},
+        {"y": 5, PlotData.INDEX_FIELD: 0, "rev": "workspace"},
+        {"y": 6, PlotData.INDEX_FIELD: 1, "rev": "workspace"},
         {"y": 3, PlotData.INDEX_FIELD: 0, "rev": "HEAD"},
         {"y": 5, PlotData.INDEX_FIELD: 1, "rev": "HEAD"},
     ]
diff --git a/tests/func/plots/test_plots.py b/tests/func/plots/test_plots.py
--- a/tests/func/plots/test_plots.py
+++ b/tests/func/plots/test_plots.py
@@ -60,8 +60,8 @@ def test_plot_csv_one_column(tmp_dir, scm, dvc, run_copy_metrics):
     plot_content = json.loads(plot_string)
     assert plot_content["title"] == "mytitle"
     assert plot_content["data"]["values"] == [
-        {"0": "2", PlotData.INDEX_FIELD: 0, "rev": "working tree"},
-        {"0": "3", PlotData.INDEX_FIELD: 1, "rev": "working tree"},
+        {"0": "2", PlotData.INDEX_FIELD: 0, "rev": "workspace"},
+        {"0": "3", PlotData.INDEX_FIELD: 1, "rev": "workspace"},
     ]
     assert plot_content["encoding"]["x"]["field"] == PlotData.INDEX_FIELD
     assert plot_content["encoding"]["y"]["field"] == "0"
@@ -86,14 +86,14 @@ def test_plot_csv_multiple_columns(tmp_dir, scm, dvc, run_copy_metrics):
         {
             "val": "2",
             PlotData.INDEX_FIELD: 0,
-            "rev": "working tree",
+            "rev": "workspace",
             "first_val": "100",
             "second_val": "100",
         },
         {
             "val": "3",
             PlotData.INDEX_FIELD: 1,
-            "rev": "working tree",
+            "rev": "workspace",
             "first_val": "200",
             "second_val": "300",
         },
@@ -119,13 +119,13 @@ def test_plot_csv_choose_axes(tmp_dir, scm, dvc, run_copy_metrics):
     assert plot_content["data"]["values"] == [
         {
             "val": "2",
-            "rev": "working tree",
+            "rev": "workspace",
             "first_val": "100",
             "second_val": "100",
         },
         {
             "val": "3",
-            "rev": "working tree",
+            "rev": "workspace",
             "first_val": "200",
             "second_val": "300",
         },
@@ -148,8 +148,8 @@ def test_plot_json_single_val(tmp_dir, scm, dvc, run_copy_metrics):
 
     plot_json = json.loads(plot_string)
     assert plot_json["data"]["values"] == [
-        {"val": 2, PlotData.INDEX_FIELD: 0, "rev": "working tree"},
-        {"val": 3, PlotData.INDEX_FIELD: 1, "rev": "working tree"},
+        {"val": 2, PlotData.INDEX_FIELD: 0, "rev": "workspace"},
+        {"val": 3, PlotData.INDEX_FIELD: 1, "rev": "workspace"},
     ]
     assert plot_json["encoding"]["x"]["field"] == PlotData.INDEX_FIELD
     assert plot_json["encoding"]["y"]["field"] == "val"
@@ -176,13 +176,13 @@ def test_plot_json_multiple_val(tmp_dir, scm, dvc, run_copy_metrics):
             "val": 2,
             PlotData.INDEX_FIELD: 0,
             "first_val": 100,
-            "rev": "working tree",
+            "rev": "workspace",
         },
         {
             "val": 3,
             PlotData.INDEX_FIELD: 1,
             "first_val": 200,
-            "rev": "working tree",
+            "rev": "workspace",
         },
     ]
     assert plot_content["encoding"]["x"]["field"] == PlotData.INDEX_FIELD
@@ -207,8 +207,8 @@ def test_plot_confusion(tmp_dir, dvc, run_copy_metrics):
 
     plot_content = json.loads(plot_string)
     assert plot_content["data"]["values"] == [
-        {"predicted": "B", "actual": "A", "rev": "working tree"},
-        {"predicted": "A", "actual": "A", "rev": "working tree"},
+        {"predicted": "B", "actual": "A", "rev": "workspace"},
+        {"predicted": "A", "actual": "A", "rev": "workspace"},
     ]
     assert plot_content["encoding"]["x"]["field"] == "predicted"
     assert plot_content["encoding"]["y"]["field"] == "actual"
@@ -380,8 +380,8 @@ def test_custom_template(tmp_dir, scm, dvc, custom_template, run_copy_metrics):
 
     plot_content = json.loads(plot_string)
     assert plot_content["data"]["values"] == [
-        {"a": 1, "b": 2, "rev": "working tree"},
-        {"a": 2, "b": 3, "rev": "working tree"},
+        {"a": 1, "b": 2, "rev": "workspace"},
+        {"a": 2, "b": 3, "rev": "workspace"},
     ]
     assert plot_content["encoding"]["x"]["field"] == "a"
     assert plot_content["encoding"]["y"]["field"] == "b"
@@ -413,8 +413,8 @@ def test_custom_template_with_specified_data(
 
     plot_content = json.loads(plot_string)
     assert plot_content["data"]["values"] == [
-        {"a": 1, "b": 2, "rev": "working tree"},
-        {"a": 2, "b": 3, "rev": "working tree"},
+        {"a": 1, "b": 2, "rev": "workspace"},
+        {"a": 2, "b": 3, "rev": "workspace"},
     ]
     assert plot_content["encoding"]["x"]["field"] == "a"
     assert plot_content["encoding"]["y"]["field"] == "b"
@@ -450,8 +450,8 @@ def test_plot_override_specified_data_source(
 
     plot_content = json.loads(plot_string)
     assert plot_content["data"]["values"] == [
-        {"a": 1, "b": 2, "rev": "working tree"},
-        {"a": 2, "b": 3, "rev": "working tree"},
+        {"a": 1, "b": 2, "rev": "workspace"},
+        {"a": 2, "b": 3, "rev": "workspace"},
     ]
     assert plot_content["encoding"]["x"]["field"] == "a"
     assert plot_content["encoding"]["y"]["field"] == "b"
@@ -518,8 +518,8 @@ def test_plot_choose_columns(
 
     plot_content = json.loads(plot_string)
     assert plot_content["data"]["values"] == [
-        {"b": 2, "c": 3, "rev": "working tree"},
-        {"b": 3, "c": 4, "rev": "working tree"},
+        {"b": 2, "c": 3, "rev": "workspace"},
+        {"b": 3, "c": 4, "rev": "workspace"},
     ]
     assert plot_content["encoding"]["x"]["field"] == "b"
     assert plot_content["encoding"]["y"]["field"] == "c"
@@ -540,8 +540,8 @@ def test_plot_default_choose_column(tmp_dir, scm, dvc, run_copy_metrics):
 
     plot_content = json.loads(plot_string)
     assert plot_content["data"]["values"] == [
-        {PlotData.INDEX_FIELD: 0, "b": 2, "rev": "working tree"},
-        {PlotData.INDEX_FIELD: 1, "b": 3, "rev": "working tree"},
+        {PlotData.INDEX_FIELD: 0, "b": 2, "rev": "workspace"},
+        {PlotData.INDEX_FIELD: 1, "b": 3, "rev": "workspace"},
     ]
     assert plot_content["encoding"]["x"]["field"] == PlotData.INDEX_FIELD
     assert plot_content["encoding"]["y"]["field"] == "b"
@@ -560,8 +560,8 @@ def test_plot_yaml(tmp_dir, scm, dvc, run_copy_metrics):
 
     plot_content = json.loads(plot_string)
     assert plot_content["data"]["values"] == [
-        {"val": 2, PlotData.INDEX_FIELD: 0, "rev": "working tree"},
-        {"val": 3, PlotData.INDEX_FIELD: 1, "rev": "working tree"},
+        {"val": 2, PlotData.INDEX_FIELD: 0, "rev": "workspace"},
+        {"val": 3, PlotData.INDEX_FIELD: 1, "rev": "workspace"},
     ]
 
 
diff --git a/tests/unit/repo/plots/test_diff.py b/tests/unit/repo/plots/test_diff.py
--- a/tests/unit/repo/plots/test_diff.py
+++ b/tests/unit/repo/plots/test_diff.py
@@ -6,10 +6,10 @@
 @pytest.mark.parametrize(
     "arg_revisions,is_dirty,expected_revisions",
     [
-        ([], False, ["working tree"]),
-        ([], True, ["HEAD", "working tree"]),
-        (["v1", "v2", "working tree"], False, ["v1", "v2", "working tree"]),
-        (["v1", "v2", "working tree"], True, ["v1", "v2", "working tree"]),
+        ([], False, ["workspace"]),
+        ([], True, ["HEAD", "workspace"]),
+        (["v1", "v2", "workspace"], False, ["v1", "v2", "workspace"]),
+        (["v1", "v2", "workspace"], True, ["v1", "v2", "workspace"]),
     ],
 )
 def test_revisions(mocker, arg_revisions, is_dirty, expected_revisions):
diff --git a/tests/unit/repo/test_repo_tree.py b/tests/unit/repo/test_repo_tree.py
--- a/tests/unit/repo/test_repo_tree.py
+++ b/tests/unit/repo/test_repo_tree.py
@@ -38,7 +38,7 @@ def test_open_in_history(tmp_dir, scm, dvc):
     dvc.scm.commit("foofoo")
 
     for rev in dvc.brancher(revs=["HEAD~1"]):
-        if rev == "working tree":
+        if rev == "workspace":
             continue
 
         tree = RepoTree(dvc)
diff --git a/tests/unit/repo/test_tree.py b/tests/unit/repo/test_tree.py
--- a/tests/unit/repo/test_tree.py
+++ b/tests/unit/repo/test_tree.py
@@ -38,7 +38,7 @@ def test_open_in_history(tmp_dir, scm, dvc):
     dvc.scm.commit("foofoo")
 
     for rev in dvc.brancher(revs=["HEAD~1"]):
-        if rev == "working tree":
+        if rev == "workspace":
             continue
 
         tree = DvcTree(dvc)

brancher: rename `working tree` -> `workspace`
Much more natural term. Was also noted by @dmpetrov while working with plots. Needed for cml release.

tests/unit/repo/plots/test_diff.py::test_revisions[arg_revisions1-True-expected_revisions1] tests/unit/repo/plots/test_diff.py::test_revisions[arg_revisions0-False-expected_revisions0]
tests/unit/repo/plots/test_diff.py::test_revisions[arg_revisions2-False-expected_revisions2] tests/func/params/test_show.py::test_show_empty tests/func/plots/test_plots.py::test_throw_on_no_metric_at_all tests/func/plots/test_plots.py::test_should_raise_on_no_template_and_datafile tests/func/plots/test_plots.py::test_plot_no_data tests/unit/repo/plots/test_diff.py::test_revisions[arg_revisions3-True-expected_revisions3] tests/func/metrics/test_show.py::test_show_empty