/ ˈbluːmɪŋ; NAmE ; ˈblʊm-/ adjective
[ only before noun ] adverb ( BrE , informal ) a mild swear word, used to emphasize a comment or a statement, especially an angry one :
What blooming awful weather!
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WORD ORIGIN
late Middle English : from bloom + -ing , used as a euphemism for bloody (I).