n. — Hockey
a disk of hard, black rubber used in (ice) hockey (see Image 1).
Type: 4. Culturally Significant — According to OED-3, puck most likely comes from the Irish English verb "puck", meaning to hit or strike (see OED-3, s.v. "puck" (n.5 1.a)), which itself is probably from the Irish "poc", a strike or blow in the game of hurling (see OED-3, s.v. "puck" (v) and "puck" (n.4)). EDD also defines puck as a "blow, esp. a blow with the horns of a goat" (see EDD, s.v. "puck" [sb.2 and v.1 1]). The term may be related to "poke", which OED-3 defines as a stroke made in cricket, with the first attestation dating back to 1853 (see OED-3, s.v. "puck" (n.5) 1.c); EDD defines "poke" as a"blow, esp. one which produces a hollow sound" (see EDD, s.v. "poke' (v.2, sb.5 and adv. 13)).
Because of the historical and cultural significance of hockey in Canada, puck has acquired special significance (see expressions such as drop the puck). It is widely acknowledged that the first organized indoor hockey game took place in Montreal in 1875 (see the quotation). Because the game was played in an enclosed space, there appears to have been apprehension on the part of potential spectators of the ball hitting the crowd. For this reason, a "flat circular piece of wood" was used instead of a ball. Indoor, organized hockey as played at the Victoria Rink in Montreal may have contributed to the replacement of the ball for the puck.
See also: hockey road apple drop the puck puck-ragging
- 1875  [Victoria Rink - A game of Hockey will be played at the Victoria Skating Rink this evening, between two nines chose from among the members. Good fun may be expected, as some of the players are reputed to be exceedingly expert at the game. Some fears have been expressed on the part of intending spectators that accidents were likely to occur through the ball flying about in too lively a manner, to the imminent danger of lookers on, but we understand that the game will be played with a flat circular piece of wood, thus preventing all danger of its leaving the surface of the ice.]
- 1886  A HOCKEY match was played on Ash Wednesday between Queen's and the Royal Military College. The game throughout was a good one, and there was a fine exhibition of skating. [...] At a quarter past three the "puck" was placed by the referee and play was begun. 
- 1895  The puck is about the size of a blacking box, made of rubber.
- 1931  Joe Martin drew Doran out and netted the puck home with a tricky shot.
- 1963  All this fits in with the name, puck. Just how it came to be called that, or by whom, nobody knows.
- 1985  "Guy got the puck over to me and I just shot the puck and I guess it went to the right place." 
- 2013  We have a whole bunch of guys who can skate and move the puck and are real dangerous offensively, but understand how the game is supposed to be played without the puck. 
Images:
Image 1: A present-day hockey puck. Source: Wikimedia Commons. Photo: MrPanyGoff