I read that the only plural in English which shares no letters with its singular form is ‘kine’, a plural for cow. I thought this was really cool until I was disappointed to be reminded that I/we and me/us also fits this description. But it’s still interesting. Plus I that the pronouns aren’t plurals in the same way … unless perhaps I clone myself and make two ‘I’s.
I’d never heard of ‘kine’ before and the OED declares it archaic, but my mother tells me it’s still often used in her cryptic crosswords.
Interestingly as well as not sharing letters with cow, it seems to have a double plural ending. In old English kine was originally ‘cy’ which became cȳna, the genitive plural of cū (cow). In Middle English this became kyn and now kine.
The Old English ‘cy’ seems to have denoted a plural, with another the pluralising ‘(e)n’ suffix added to this. This shows the same plural ending as other irregular plurals, such as children and oxen.
This TED video gives a short, simplified video about plurals which was a fun little watch: