(n.) a loyal follower or assistant; a sidekick
We might be named after a bird, but horses keep popping up on Haggard Hawks a lot more than we might expect—often in the most bizarre of places, too. I mean, you can’t even ice a cake without a horse turning up, just like you can’t even feague a horse without an eel turning up.
And then there’s this:
So. Henchman? Horseman? What’s going on there?
Well, the “hench” in henchman comes from the Old English word hengest, meaning “stallion” or, more generally, “horse”. A henchman was originally a hengestman when the term first emerged in the fourteenth century, but because that’s a bit of a mouthful (and because its roots in Old English steadily dwindled into obscurity over time) hengest morphed into the more straightforward element hench, and that eventually established itself as the dominant form by the end of the 1500s.
The word henchmen itself then dwindled into relative obscurity, surviving for a time only in a handful of northern English and Scots dialects as a word for an (originally mounted) attendant to chief gillie, or Highland nobleman. It was in this sense that the word was picked up by Sir Walter Scott, who used a Scots-influenced form, haunchman or hanchman, in several of his novels in the nineteenth century. Before long—thanks almost single-handedly to the popularity of Scott’s novels in Victorian England—the word had slipped back into the mainstream, rescued from the linguistic scrap heap, and re-established itself as a go-to word for a supporter or right-hand-man. Its connections to horses by that time long lost to the etymological footnotes.