Slew has a divided etymological history: The noun 'large number' is from Irish slua ('crowd, multitude'); the verb 'twist, swing around' is of uncertain origin; as a verb form it is the past tense of slay (Old English slean). The historical chain includes Irish slua. Older glosses in the chain include "large number", "crowd, multitude", and "twist, swing around", which help explain the semantic range of the modern word. Morphologically, slew is best read as uncertain formation, yielding an English noun and verb shaped by both form history and later usage. In current English it functions as a noun and verb, with the sense "a large number or quantity; also past tense of slay". related forms include slay. The result is an English noun and verb whose etymology preserves the older forms while supporting the word's specialized modern meaning.