An oxen
I must be in a posting frenzy, but oh well. I was just talking to my mom about cooking, and the discussion moved to bouillon cubes, like this:

I said, “Is that supposed to be a cow?” and her response? “It’s an oxen, Linda.”
Oooh, that’s generalization of the irregular (dare I say archaic?) plural to the singular! Maybe it’s just me, but I thought it was noteworthy, since I’d otherwise expect people to forget ‘oxen’ entirely and use ‘ox’ or ‘oxes’ as the plural but leave the singular alone. Way to go, mom!