(physics) a situation in which the frequency is higher ("bluer") than the resonance frequency

(chiefly UK) A permanent sign installed in a public place to commemorate a historical link between that location and a famous person, event, or former building on the site.

plural of blue plaque

Sporting colours awarded by a university or other institution for the highest level of sporting achievement, especially and originally at Oxford and Cambridge Universities in England; contrasted with half blue.

Sporting colours awarded by a university or other institution for sporting achievement at a lower level, or in a more minor sport, than that required to receive a full blue, especially and originally at Oxford and Cambridge Universities in England.

(historical) A foreign exchange certificate issued to visitors to North Korea from capitalist countries.

plural of blue bag

A lawyer's bag made of blue fabric to carry briefs, now as typically carried by a junior barrister. / A bag containing alkaline blue laundry powder, used for whitening clothes.

(colloquial) A person who has chronic bronchitis.

plural of blue bloater