Etymology
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trap (n.)

"contrivance for catching unawares," late Old English træppe, treppe "snare, trap," from Proto-Germanic *trep- (source also of 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.)).

This is probably literally "that on or into which one steps," from PIE *dreb-, an extended form of a root *der- (1), base of words meaning "to run, walk, step." The English word is probably akin to Old French trape, Spanish trampa "trap, pit, snare," but the exact relationship is uncertain.

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

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hall (n.)

Old English heall "spacious roofed residence, house; temple; law-court," any large place covered by a roof, from Proto-Germanic *hallo "covered place, hall" (source also of Old Saxon, Old High German halla, German halle, Dutch hal, Old Norse höll "hall;" Old English hell, Gothic halja "hell"), from PIE root *kel- (1) "to cover, conceal, save."

Sense of "passageway in a building" evolved 17c., from the time when the doors to private rooms opened onto the large public room of the house. Older sense preserved in town hall, music hall, etc., in use of the word in Britain and Southern U.S. for "manor house," also "main building of a college" (late 14c.). French halle, Italian alla are from Middle High German. Hall of fame attested by 1786 as an abstract concept; in sporting sense first attested 1901, in reference to Columbia College; the Baseball Hall of Fame opened in 1939. Related: Hall-of-famer.

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