incompetent, incompetent person - someone who is not competent to take effective action

error, mistake, fault - a wrong action attributable to bad judgment or ignorance or inattention; "he made a bad mistake"; "she was quick to point out my errors"; "I could understand his English in spite of his grammatical faults"

snafu - an acronym often used by soldiers in World War II: situation normal all fucked up

spectacle - a blunder that makes you look ridiculous; used in the phrase `make a spectacle of' yourself

bull - a serious and ludicrous blunder; "he made a bad bull of the assignment"

fumble, muff - (sports) dropping the ball

fluff - a blunder (especially an actor's forgetting the lines)

faux pas, gaffe, slip, solecism, gaucherie - a socially awkward or tactless act

howler - a glaring blunder

clanger - a conspicuous mistake whose effects seem to reverberate; "he dropped a clanger"

misstep, trip-up, stumble, trip - an unintentional but embarrassing blunder; "he recited the whole poem without a single trip"; "he arranged his robes to avoid a trip-up later"; "confusion caused his unfortunate misstep"