Jolly Roger (JOL-ee ROJ-uhr) noun The pirates' flag, showing a white skull and crossbones on a black background. Also known as the blackjack or black flag. [The origin of the name Jolly Roger is uncertain.] Today's word in Visual Thesaurus: http://visualthesaurus.com/?w1=jolly+roger -Guest Wordsmith... Sign in to see full entry.