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English definition of “blue”

blue

adjective [after verb] (SAD)    /bluː/ informal
C2 feeling or showing sadness: He's been a bit blue since he failed his exams. → See also have the bluesFeeling sad and unhappy blueness     /ˈbluː.nəs/ noun [U] Common coloursLess common colours
(Definition of blue adjective (SAD) from the Cambridge Advanced Learner's Dictionary & Thesaurus © Cambridge University Press)
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