scut (n.1)

"short, erect tail" (of a rabbit, hare, deer, etc.), 1520s; earlier "a hare" (mid-15c., perhaps c. 1300), a word of obscure origin.

Perhaps it is from Old Norse skjota "to shoot (with a weapon), launch, push, shove quickly" (compare Norwegian skudda "to shove, push"), from PIE root *skeud- "to shoot, chase, throw." Or perhaps it is a relative of Middle English sheten "hasten from one place to another," from Old English sceotan, sceotian, from Proto-Germanic *skeutanan (source also of Old Frisian skiata "to shoot, supply," Old Dutch scietan), for which Boutkan offers no IE etymology.

Also compare Middle English scut (v.) "make short, hurried runs," as a noun, "a short garment" (mid-15c.), as an adjective, "short" (c. 1200), perhaps from Old French escorter, from Latin excurtare.

term of contempt for a person, 1873, of unknown etymology. OED suggests it is a variant of scout (v.2).