A lot vs. Alot: 9 Grammatical Pitfalls
early 15c., "defense, justification," from Late Latin apologia, from Greek apologia "a speech in defense," from apologeisthai "to speak in one's defense," from apologos "an account, story," from apo- "from, off" (see apo-) + logos "speech" (see lecture (n.)).
The original English sense of "self-justification" yielded a meaning "frank expression of regret for wrong done," first recorded 1590s, but this was not the main sense until 18c. The old sense tends to emerge in Latin form apologia (first attested in English 1784), especially since J.H. Newman's "Apologia pro Vita Sua" (1864).