Originally Posted by HareBrain
The only Latin I know comes from Monty Python's Life of Brian, but isn't the male ending "us"? (As confusion over the gender of a certain bear has shown.) So focus/foci, locus/loci, pokeintheus/pokeinthei.
If stadium/stadia, why not forum/fora?
I ought to decline to comment, but as with English (and other languages') verbs, endings are often reused. This is easiest to see with adjectives, which have to have versions for all three genders as well as the six cases**:
.......M.......F.......NAcc. bonum ..bonam ..bonum
Nom. bonus ..bona ...bonum
Gen. boni ...bonae ..boniAbl. bono ...bona ...bono Voc. bone ...bona ...bonum
Dat. bono ...bonae ..bono
PluralNom. boni ...bonae ..bona
Acc. bonos ..bonas ..bonaVoc. boni ...bonae ..bona
Gen. bonorum bonarum bonorum
Dat. bonis ..bonis ..bonis
Abl. bonis ..bonis ..bonis
(I hope no-one will suggest that Boneman has a feminine plural accusative. )
** - Nominative (subject), Accusative (direct object), Genitive (possessive), Dative (indirect object), Ablative (used with objects that in English are preceded by: with, to, for, in, on...), Vocative (used to address someone - or something - in speech). Someone else can deal with the Locative.