'Jolly Roger' definitions:

Definition of 'Jolly Roger'

From: WordNet
noun
A flag usually bearing a white skull and crossbones on a black background; indicates a pirate ship [syn: black flag, pirate flag, Jolly Roger, blackjack]

Definition of 'Jolly Roger'

From: GCIDE
  • Roger \Rog"er\, n. [From a proper name Roger.] A black flag with white skull and crossbones, formerly used by pirates; -- called also Jolly Roger and pirate flag. [Webster 1913 Suppl. +PJC]