pl of sinus.
2. sinus ·noun a cavity; a depression.
3. sinus ·noun a dilated vessel or canal.
4. sinus ·noun an opening; a hollow; a bending.
5. sinus ·noun a depression between adjoining lobes.
6. sinus ·noun a bay of the sea; a recess in the shore.
7. sinus ·noun a cavity in a bone or other part, either closed or with a narrow opening.
8. sinus ·noun a narrow, elongated cavity, in which pus is collected; an elongated abscess with only a small orifice.