trap (v.) Look up trap at Dictionary.com
late 14c., "ensnare (an animal), catch in a trap; encircle; capture," from trap (n.) or from Old English betræppan. Figurative use is slightly earlier (late 14c.). Related: Trapped; trapping.
trap (n.) Look up trap at Dictionary.com
"contrivance for catching unawares," late Old English træppe, treppe "snare, trap," from Proto-Germanic *trep- (cognates: Middle Dutch trappe "trap, snare"), related to Germanic words for "stair, step, tread" (Middle Dutch, Middle Low German trappe, treppe, German Treppe "step, stair," English tread (v.)), and probably literally "that on or into which one steps," from PIE *dreb-, extended form of root *der- (1), an assumed base of words meaning "to run, walk, step." Probably akin to Old French trape, Spanish trampa "trap, pit, snare," but the exact relationship is uncertain.

Sense of "deceitful practice, device or contrivance to betray one" is first recorded c.1400. Meaning "U-shaped section of a drain pipe" is from 1833. Slang meaning "mouth" is from 1776. Speed trap recorded from 1908. Trap door "door in a floor or ceiling" (often hidden and leading to a passageway or secret place) is first attested late 14c.