Why is the ninth month called September?
1640s (intransitive), 1753 (transitive), back formation from regurgitation, or else from Medieval Latin regurgitatus, past participle of regurgitare. Meaning "to vomit" first attested 1753. Related: Regurgitated; regurgitating.
regurgitate re·gur·gi·tate (rē-gûr'jĭ-tāt')
v. re·gur·gi·tat·ed, re·gur·gi·tat·ing, re·gur·gi·tates
To rush or surge back.
To cause to pour back, especially to cast up partially digested food.