"frame turning on an axis," especially one on which thread is wound, late Old English hreol "reel for winding thread," from Proto-Germanic *hrehulaz; probably related to hrægel "garment," and Old Norse hræll "spindle," from PIE *krek- "to weave, beat" (source also of Greek krokus "nap of cloth").

Specifically of the fishing rod attachment from 1726; of a film projector apparatus from 1896. Reel-to-reel type of tape deck is attested from 1958.