WordNet sense 1 (a horse's bit with an attached chain or strap to check the horse):

curb bit

WordNet sense 2 (an edge between a sidewalk and a roadway consisting of a line of curbstones (usually forming part of a gutter)):

curbing, kerb

WordNet sense 3 (a stock exchange in New York):

AMEX, American Stock Exchange

WordNet sense 4 (lessen the intensity of; temper; hold in restraint; hold or keep within limits):

check, contain, control, hold, moderate, moderate, hold in

WordNet sense 5 (the act of restraining power or action or limiting excess):

bridle

WordNet sense 6 (to put down by force or authority):

conquer, inhibit, subdue, suppress, stamp down

WordNet sense 7 (place restrictions on):

curtail, restrict, cut back