SI'NUS, noun [Latin a bay.] 1. A bay of the sea; a recess in the shore , or an opening in the land. 2. In anatomy, a cavity in a bone or other part, wider at the bottom than at the entrance. 3. In surgery, a little cavity or sack in which pus is collected; an abscess with only a small orifice. 4. An opening; a hollow.
Source: Webster's 1828 American Dictionary ↗ · public-domain · returned verbatim, no AI