THESAURUS
blow the whistle
arrest, bear witness against, betray, blab, block, brake, bring to, bring up short, call a halt, check, checkmate, cut short, dam, deadlock, draw rein, fink, freeze, halt, have had it, inform against, inform on, lose patience, narc, peach, pull up, put paid to, rat, sell out, snitch, snitch on, squeal, stalemate, stall, stay, stem, stem the tide, stool, stop, stop cold, stop dead, stop short, tattle, tell on, testify against, turn informer
