The story
From Latin ratis (“raft”) + -ite; ratites (unlike other birds) lack a keel on their sternum, and rafts are vessels that lack keels.
First known use, by meaning
- from 19th c. Pertaining to running, flightless birds with no keels on their sternums (as opposed to carinate).
Etymology from Wiktionary, CC BY-SA 4.0.