Squirrel
Middle English: shortening of Old French esquireul, from a diminutive of Latin sciurus, from Greek skiouros, from skia ‘shade’ + oura ‘tail’. Current verb senses date from the early 20th century.
wiktionary
From Middle English squirel, squyrelle, from Anglo-Norman esquirel and Old French escurel (whence French écureuil), from Vulgar Latin *scūriolus, diminutive of *scūrius, variant of Latin sciūrus, from Ancient Greek σκίουρος(skíouros) "shadow-tail", from σκιά(skiá, “shadow”) + οὐρά(ourá, “tail”).
Displaced native Middle English acquerne, aquerne, from Old English ācweorna.
etymonline
squirrel (n.)
early 14c., from Anglo-French esquirel, Old French escurueil "squirrel; squirrel fur" (Modern French écureuil), from Vulgar Latin *scuriolus, diminutive of *scurius "squirrel," variant of Latin sciurus, from Greek skiouros "a squirrel," literally "shadow-tailed," from skia "shadow" (see Ascians) + oura "tail," from PIE root *ors- "buttocks, backside" (see arse). Perhaps the original notion is "that which makes a shade with its tail," but Beekes writes that this "looks like a folk etymology rather than a serious explanation." The Old English word was acweorna, which survived into Middle English as aquerne.
squirrel (v.)
"to hoard up, store away" (as a squirrel does nuts), 1939, from squirrel (n.). Related: Squirreled; squirreling.
