Save. sedimentary /ˌsɛdəˈmɛntəri/ adjective. sedimentary. /ˌsɛdəˈmɛntəri/. adjective. Learner's definition of SEDIMENTARY. technical. : made from material that sinks to the bottom of a liquid: made from sediment. sedimentary layers/deposits. Sandstone is a sedimentary rock. [=a type of rock formed when sediments that were deposited in ancient times were pressed together and became hard]. [+] more examples [-] hide examples [+] Example sentences [-] Hide examples. Comments & Questions. Comments & Questions.