(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.

(informal) Blue eyes.

(informal) Period and feeling of depressiveness after giving birth; a less severe form of postnatal depression.

A very dark blue. / Black with bluish highlights.

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

A dark, bluish-grey colour.

Of a dark, bluish-grey colour.

A brilliant, dark blue-green colour, like the plumage of a peacock.

Of a brilliant blue-green colour.