That last post leads to the question of just why are cows called bossie, as a cat is a tabby? (We mostly don’t eat cat, so let’s let tabby go for the present.) One explanation, quick and simple, from the Purebred Dexter Cattle Association of NA:
The Latin word for ox or cow is bos
Another, more lengthy one from WorldWideWords and the British perspective is
One theory has it that the noun is from West Country dialect. The word boss is known from the eighteenth century, sometimes as buss or buss-calf or bussa, a name that was given to a young, unweaned calf. It’s suggested that this word was taken to North America by some of the pioneering immigrants. The other theory suggests that bossy might have come from the Latin bos for an ox or cow (it’s the source of the word bovine that I used earlier). Just possibly, the West Country dialect word might also have come from the Latin term, though it seems an obscure and literary word to have been taken up in dialect. If that theory is right, no matter which of the two theories you pick, you end up in Latin.
As usual, nobody’s prepared to put any money on one or the other. Bossy is too poorly recorded in its early years for it to be clear what was going on in people’s minds at the time.
I think I’ll stick with the first one.