Old English segl "sail, veil, curtain," from Proto-Germanic *seglom (source also of Old Saxon, Swedish segel, Old Norse segl, Old Frisian seil, Dutch zeil, Old High German segal, German Segel), of obscure origin with no known cognates outside Germanic (Irish seol, Welsh hwyl "sail" are Germanic loan-words). In some sources (Klein, OED) referred to PIE root *sek- "to cut," as if meaning "a cut piece of cloth." To take the wind out of (someone's) sails (1888) is to deprive (someone) of the means of progress, especially by sudden and unexpected action, "as by one vessel sailing between the wind and another vessel," ["The Encyclopaedic Dictionary," 1888].