ˌunderˈhorsed,a. (under-1 10 a.) 1860Cornh. Mag. Dec. 689 Why won't he get something able to carry him?.. It's the stupidest thing in the world to be under-horsed.1887Illustr.Lond. News 24 Sept. 360/2 That such an institution [sc. the fire-brigade]..should..be underhorsed and undermanned.