Origin and history of sly

sly(adj.)

late 12c., sleigh, "skillful, clever, dexterous, wise, prudent," from Old Norse sloegr "cunning, crafty, sly," from Proto-Germanic *slogis (source also of Low German slu "cunning, sly," German schlau), probably from *slak- "to strike, hit" (see slay (v.)), with an original notion of "able to hit." Compare German verschlagen "cunning, crafty, sly," schlagfertig "quick-witted," literally "strike-ready," from schlagen "to strike," but the exact relation is uncertain.

The meaning "insidious, crafty, meanly artful" is from c. 1200. That of "playfully artful, knowing" is from 1764. In Middle English sly words could mean "wise words" or "deceptive language." A non-pejorative use of the word lingered in northern English dialect until 20c. On the sly "in secret" is recorded from 1812. Sly-boots "a seeming Silly, but subtil Fellow" is in the 1700 "Dictionary of the Canting Crew."

also from late 12c.

Entries linking to sly

slay(v.)

Middle English slēn, "strike, beat, strike so as to kill, commit murder," from Old English slean "to smite, strike, beat," also "to kill with a weapon, slaughter" (class VI strong verb; past tense sloh, slog, past participle slagen), from Proto-Germanic *slahanan "to hit" (source also of Old Norse and Old Frisian sla, Danish slaa, Middle Dutch slaen, Dutch slaan, Old High German slahan, German schlagen, Gothic slahan "to strike"). The Germanic words are said to be from PIE root *slak- "to strike" (source also of Middle Irish past participle slactha "struck," slacc "sword"), but, given certain phonetic difficulties and that the only cognates are Celtic, Boutkan says the evidences "point to a North European substratum word."

The verb slēn displays many nondialectal stem variants because of phonological changes and analogical influences both within its own paradigm and from other strong verbs. [Middle English Compendium]

Modern German cognate schlagen maintains the original sense of "to strike."

It is attested by late 12c. as "destroy, put an end to." The meaning "overwhelm with delight" (mid-14c.) preserves one of the wide range of meanings the word once had, including, in Old English, "stamp (coins); forge (weapons); throw, cast; pitch (a tent), to sting (of a snake); to dash, rush, come quickly; play (the harp); gain by conquest."

sleight(n.)

an early 14c. alteration of sleahthe "wisdom, prudence," also "cleverness, cunning" (c. 1200), from Old Norse sloegð "cleverness, cunning, slyness," from sloegr (see sly). The meaning "feat or trick requiring quickness and nimbleness of the hands" is from 1590s. Term sleight of hand for the tricks of a juggler is attested from c. 1400. Related: Sleighty.