scud v.

"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.

the modern English word is a merger of two words, both in Middle English as quashen, from two unrelated Latin verbs.

1. "to suppress, overcome" (mid-13c.); "to make void, annul, nullify, veto" (mid-14c.), from Old French quasser, quassier, casser "to annul, declare void," and directly from Medieval Latin quassare, alteration of Late Latin cassare, from cassus "null, void, empty" (from extended form of PIE root *kes- "to cut"). The meaning "subdue, put down summarily" is from c. 1600.

2. "to break, crush, beat to pieces" early 14c., from Old French quasser, casser "to break, smash, destroy; maltreat, injure, harm, weaken," from Latin quassare "to shatter, shake or toss violently," frequentative of quatere (past participle quassus) "to shake," from PIE root *kwet- "to shake" (source also of Greek passein "to sprinkle," Lithuanian kutėti "to shake up," Old Saxon skuddian "to move violently," German schütteln "to shake," Old English scudan "to hasten").

In Medieval Latin, quassare often was used for cassare, and in later French the form of both words is casser. The words in English now are somewhat, or entirely, fused. Related: Quashed; quashing.

"run hurriedly, scamper, scurry," mid-15c. (implied in scuttling), probably related to or a frequentative form of scud (v.). Also compare scut (n.1). Related: Scuttled.

I should have been a pair of ragged claws

Scuttling across the floors of silent seas.

[T.S. Eliot, from "The Love Song of J. Alfred Prufrock"]

As a noun, "a short, hurried run," by 1620s.