The term 'billiards-stroke' refers to the various techniques used in the game of billiards. Sidespin, with 8 letters, is a technique used to impart spin on the cue ball by striking it off-center. Masse, with 5 letters, is a shot that involves hitting the cue ball with a raised cue stick in order to cause it to curve in a particular direction. CANNON, with 6 letters, is a shot in which two balls are struck simultaneously. Finally, CAROM, with 5 letters, is a shot in which the cue ball strikes two other balls in succession. All of these techniques are important for playing billiards and mastering them can help players improve their game.