It is, on the whole, advisable to make the pump of flint glass, or at all events the air-trap tube and the fall tubes.
"contrivance for catching unawares," late Old English træppe "snare, trap," from Proto-Germanic *trap- (cf. Middle Dutch trappe "trap, snare"), related to Germanic words for "stair, step, tread" (cf. Middle Dutch, Middle Low German trappe, treppe, German Treppe "step, stair"). Probably akin to Old French trape, Spanish trampa "trap, pit, snare," but the exact relationship is uncertain. The connecting notion seems to be "that on which an animal steps." Sense of "deceitful practice, trickery" is first recorded c.1400. Sense in speed trap recorded from 1906. Slang meaning "mouth" is from 1776. Trap door "door in a floor or ceiling" (often hidden and leading to a passageway or secret place) is first attested late 14c.
c.1400, "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.
: to figure out why my trap money was shitty (1970s+ Black)