Simple past tense and past participle of bum.(verb)
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Use "bummed" in a sentence
"Dang ... grizzly bear AND a PIG ROAST! i'm so fuggin bummed out i am gunna miss this east coast deliciousness ..."
"Ticker tapes, blaring cable news network updates, and new advertising overlays all bespeak a bummed out bear market that never bounced back."
"He was a good student in high school, and he was voted "best looking" by the class, a title that bummed him out because he wanted to win "best partier.""