Entry 1 sense Webster, 1913 Sedimentary /sĕdˌ-əm-ĕn'-tẽr-ē/ · Sed·i·men·ta·ry · IPA /ˌsɛd.əˈmɛn.tə.ɹi/ 01 a. Of or pertaining to sediment; formed by sediment; containing matter that has subsided. 1. Of or pertaining to sediment; formed by sediment; containing matter that has subsided. Phrases & compounds Sedimentary rocks — See Aqueous rocks, under Aqueous.