1630s, a tool for winding the spring of a wheel-lock firearm, from GermanSpanner, fromspannen "to join, fasten, extend, connect," from Proto-Germanic*spannan, from PIE root*(s)pen- "to draw, stretch, spin" (source also ofspin (v.)). Meaning "wrench" is from 1790. Figurative phrasespanner in the works attested from 1921 (Wodehouse).
