Getting all the nodes NOT tagged with a taxonomy term
Create a new views page
Select/Add the node related fields that you would like to refer while filtering the nodes.
Add a filter to filter the nodes by content type
Add a filter: Taxonomy term: Term
Select: Expose this filter to visitors, to allow them to change it
Select: 'Expose operators' and 'Reduce duplicates'
Save the filter and view.
Now go run the url of the views page.


You will see the filter at the top of node fields.
1. Select the filter as (Operator: Is none of) and select the term (Term 1) as per your eg.
2. Click apply button
3. You will see all the nodes which are not tagged to Term 1