(n.) The slender recoil spring which regulates the motion of the balance in a timepiece.

act drop asbestos asbestos board backdrop balance balance rudder balance wheel ballast batten border cloth consideration coulisse counterbalance counterblast countercurrent counterforce counterinfluence counterpoise counterpressure crosscurrent curtain curtain board cyclorama decor drop drop curtain equipoise equivalent fin fire curtain fixative flat flipper flywheel foul wind give-and-take governor gyroscope hairspring hanging head wind keel makeweight mordant offset pendulum quid pro quo rag scene scenery screen setoff shock absorber side scene something of value springs stabilizator stage screw stiffening tab tableau tail plane teaser tit for tat tormentor transformation transformation scene undercurrent wing wingcut woodcut