billiard

Etymology 1

From French billard, originally referring to the wooden cue stick, diminutive of Old French bille (“log, tree trunk”), from Vulgar Latin *bilia, probably of Gaulish origin (compare Old Irish bile (“large tree, tree trunk”)), from Proto-Celtic *belyos (“tree”), from Proto-Indo-European *bʰolh₃yos (“leaf”), from *bʰleh₃- (“blossom, flower”).

noun

1. A shot in billiards or snooker in which the cue ball strikes two other balls; a carom.
2. (attributive) Pertaining to the game of billiards.
   a billiard table; a billiard ball
3. A dynamical system in which a particle alternates between motion in a straight line and specular reflections from a boundary.

Etymology 2

From French billiard, equivalent to bi- (“two”) + -illiard.

num

1. (Britain, rare) 10¹⁵, a thousand billion (long scale) or a million milliard.