Depress, sadden, dispirit, as in He's been really bummed out since his girlfriend moved to California. [Slang; late 1960s]
Annoy, irritate, vex, as in That haircut will really bum out his parents. [Slang; c. 1970]
Fail badly, as in I got through the midterm, but I bummed out totally on the final exam. This usage is student slang. [Late 1960s]
How to use bum out in a sentence
Really, is it any wonder that fluoride should freak people out?
For a while yoga and pilates classes were sought out at luxury gyms like Equinox.How Taryn Toomey’s ‘The Class’ Became New York’s Latest Fitness Craze|Lizzie Crocker|January 9, 2015|DAILY BEAST
On Thursday, Garcetti ruled himself out of the race to succeed Boxer.The Golden State Preps for the ‘Red Wedding’ of Senate Races|David Freedlander|January 9, 2015|DAILY BEAST
Police officials told the AP that they came out with guns blazing.
“I think for trans men who are dating every time they hook up they have another coming out,” Sandler said.
And he was gone, and out of sight on the swift galloping Benito, before Father Gaspara bethought himself.Ramona|Helen Hunt Jackson
Most of the men leaped up, caught hold of spears or knives, and rushed out.The Giant of the North|R.M. Ballantyne
Liszt looked at it, and to her fright and dismay cried out in a fit of impatience, "No, I won't hear it!"Music-Study in Germany|Amy Fay
The most High hath created medicines out of the earth, and a wise man will not abhor them.The Bible, Douay-Rheims Version|Various
Squinty could look out, but the slats were as close together as those in a chicken coop, and the little pig could not get out.Squinty the Comical Pig|Richard Barnum