blue peter

noun

Nautical.

1. a blue flag with a white square in the center, designating the letter P in the International Code of Signals, flown by a vessel in port to indicate its imminent departure.

blue peter

noun

1. a signal flag of blue with a white square at the centre, displayed by a vessel about to leave port

Word History and Origins

Origin of blue peter¹

First recorded in 1815–25

Word History and Origins

Origin of blue peter¹

C19: from the name Peter