Slow Whistle Definition

noun
In hockey, soccer, and similar sports, a situation in which an official prepares to blow a whistle in order to call a rule infraction but delays to see how the play develops, as when the team not about to be penalized has a scoring opportunity.
American Heritage
A situation in which an official is slow to blow a whistle to stop play, as when a hockey goalie has covered up the puck.
American Heritage