Of the color of the pigment zaffre.

(idiomatic, US politics) A state of the United States voting Democratic in a given election, or tending to vote Democratic in general.

(idiomatic) unexpectedly; without warning or preparation.

Originally, the flag of the Rear Admiral's squadron in the English fleet.

(nautical) A trophy for the fastest sea crossing of the Atlantic by a liner. / (motorcycling) An award from the British Motorcycling Federation for advanced riding.

(nautical) 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.

(card games, intransitive) In whist, to play a blue peter.

(ice hockey) Either of the two thick blue lines on the ice that separate an attacking zone or defending zone from the neutral zone.

A very dark blue. / Black with bluish highlights.

Of a very dark blue. / Black with bluish highlights.