say it: BUHM-ur
bummer is a noun meaning "an experience that is irritating or frustrating or disappointing". It carries 2 recorded senses.
an experience that is irritating or frustrating or disappointing
“having to stand in line so long was a real bummer”
a bad reaction to a hallucinogenic drug
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for bummer come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.