Flag showing ship is about to leave

Wikipedia Word definitions in Wikipedia
" Blue Peter " is a single by musician Mike Oldfield , released in 1979. It is a rendition of the theme tune for the British children's television show Blue Peter and was used by the show between 1979 and 1989.

WordNet Word definitions in WordNet
n. a blue flag with a white square in the center indicates that the vessel is ready to sail

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Blue \Blue\ (bl[=u]), a. [Compar. Bluer (bl[=u]"[~e]r); superl. Bluest .] [OE. bla, blo, blew, blue, livid, black, fr. Icel.bl[=a]r livid; akin to Dan. blaa blue, Sw. bl[*a], D. blauw, OHG. bl[=a]o, G. blau; but influenced in form by F. bleu, from OHG. ...

Wiktionary Word definitions in Wiktionary
n. (context nautical English) A blue signal flag with a white rectangle in the centre, signifying "P". When flown alone, indicates that a ship is ready to sail, requiring all crew members and passengers to return on board.