An extensive bridge consisting, strictly of a series of arches of masonry, erected for the purpose of conducting a road or a railway a valley or a district of low level, or over existing channels of communication, where an embankment would be impracticable or inexpedient; more widely, any elevated roadway which artificial constructions of timber, iron, bricks, or stonework are established. [Century Dictionary]
But the word apparently was coined by English landscape gardener Humphry Repton (1752-1818) for an architectural feature, "a form of bridge adapted to the purposes of passing over, which may unite strength with grace, or use with beauty ...."
1640s, "that which borders on something else, the part abutting on or against," from abut (v.) + -ment. Originally any junction; the architectural usage, "solid structure where one arch of a bridge, etc., meets another" is attested from 1793 (the notion is of the meeting-place of the arches of a bridge, etc.).
"flat-bottomed, square-ended, mastless river boat," c. 1500, perhaps a local survival of late Old English punt, which probably is from British Latin ponto "flat-bottomed boat" (see OED), a kind of Gallic transport (Caesar), also "floating bridge" (Gellius), from Latin pontem (nominative pons) "bridge" (from PIE root *pent- "to tread, go;" see find (v.)). Or from or influenced by Old French cognate pont "large, flat boat." Compare pontoon.
tile-based game originally from China, 1922, from dialectal Chinese (Shanghai) ma chiang, name of the game, literally "sparrows," from ma "hemp" + chiang "little birds." The game so called from the design of the pieces. It had a vogue in Europe and the U.S. 1922-23 and for a time threatened to supplant bridge in popularity.