Just came across the expression “bettors” in a Bloomberg report, which I can’t recall having seen before: “gamblers” would be my BrE usage, and a quick check on Google News suggests this is entirely or almost entirely indeed a North American usage. The OED entry for “bettor” hasn’t been updated since 1887, alas, so while it says Ben Jonson and Joseph Addison used the word, which is respectable enough for anyone, it doesn’t give any clues to modern usage.  Any other Britons familiar with “bettor”? (It seems originally to have been spelled “better”, though for obvious homographic reasons the “-or’ version now seems to have prevailed.)

It is a term used in laws and regulations in Australia, the kind of word that might appear in a formal agreement but not a word that any normal person would say.

Diegogarcity strikes. I’d just been impressed all over again with Marie Windsor in the original version of The Narrow Margin (1952) and I was scoping out other movies she’d appeared in when lo and behold up popped this from 1951, Two Dollar Bettor. I am familiar with the word both from my reading and, I seem to recall, from the bookies, although as I haven’t frequented those establishments for a couple of decades I could well be misremembering there.