Succubus & incubus don't show up in the Latin dictionaries I've searched. I'm wondering what the plurals would be. I did find succuba, 1st decl fem. Could it be that it didn't morph into a 2nd decl look-alike until it came into English? Or could it be an unusual 4th declension?
Are you looking for the plurals in English, or Latin?– Draconis ♦Apr 1, 2021 at 22:34
English, but by way of getting clear what the Latin might be..– MrEdApr 2, 2021 at 15:53
According to Wiktionary, succubus evolved in Middle English from the Latin word succuba, one who lies under. The plural is given in the aforementioned Wiktionary as succubi or succubuses. Personally, I've usually only seen the former used (or maybe I just prefer that plural).
Incubus, however, came from the late Latin word incubus which evolved from incubo, to lie upon. The plural given by Wiktionary is the same as succubus: incubi, incubuses.
1Pretty much what I was guessing. Succuba morphed to Succubus when it came into English. I'm with you in choosing succubi and incubi as the better plural form.– MrEdApr 2, 2021 at 15:55
I have not yet figured out how to mark things "accepted"– MrEdApr 2, 2021 at 16:03
Beneath the voting button should be a checkmark - click on that and it will mark that answer as accepted. You can also read more about accepting answers on the StackExchange meta.– AdamApr 2, 2021 at 16:19