Are there any words in English that have a plural with a separate derivation?

Solution 1:

Notwithstanding that I voted to close, I'm going to stick my neck out and say there are no "English nouns with suppletive plurals". With the possible exception of person/people per Wiktionary link.

But I would point out that both those are singular words in their own right, with regular plurals (persons/peoples). It just so happens that people is often used as a plural anyway (similar to one fish, two fish).

It's also worth noting that person can be used in contexts where people can't - for example, "He carries a pistol on his person", but not *"They carry pistols on their people". Correspondingly, "The good people of London welcome all to the Olympics", but not *"The good persons of London..."

Valid examples of suppletion in English consist of a few common verbs (to be - am, is, were, are) and adjectives (good - better, best). The phenomenon can only occur with common words, because with uncommon words the natural tendency of speakers to "regularise" inflections will triumph.

Solution 2:

The following pairs have plurals with stems different from those of the singular forms:

Personal pronouns

I and we

he/she/it and they

Possessive pronouns

mine and ours

his/hers and theirs

Possessive determiners

my and our

his/her/its and their.

Solution 3:

I think person/people is as close (or far) as it gets.

Solution 4:

Person/people.

Both words have additional plurals as well.

Solution 5:

Cow has three plurals: cows (which comes from "cow"), cattle (from from Anglo-Norman catel, meaning "chattel"), and kine (which comes from ku, also the ancient root of "cow", so might not count).