I don't think "index" is a Latin word? You're probably asking the wrong person, I am quite comfortable to say indexes, and indeed sheeps -- it's an English word

I don't think "index" is a Latin word? You're probably asking the wrong person, I am quite comfortable to say indexes, and indeed sheeps -- it's an English word I can just put the -S noise at the end to pluralize it and that'll be fine even if (as with ox) there is a special case rule that some people insist matters for this word or that one. Likewise I'm comfortable with "Can't nobody prove nothing", which I think is a succinct way to express an opinion that would be rather awkward when expressed in the prestige dialects of English instead.