Definition of sinus

• pl. - of Sinus
• n. - An opening; a hollow; a bending.
• n. - A bay of the sea; a recess in the shore.
• n. - A cavity; a depression.
• n. - A cavity in a bone or other part, either closed or with a narrow opening.
• n. - A dilated vessel or canal.
• n. - A narrow, elongated cavity, in which pus is collected; an elongated abscess with only a small orifice.
• n. - A depression between adjoining lobes.