Blunder

Blunder-n
a serious or embarrassing mistake, usually the result of carelessness or ignorance

v
1-(vi) to make a serious or embarrassing mistake as a result of carelessness or ignorance
2-(vi) to stumble or move clumsily
3-(vti) to act in a manner that is clumsy, ignorant, or thoughtless
4-(vti) to say or write something in a clumsy or thoughtless way

Synonyms
mistake
slip-up
error
mix-up
gaffe
bungle
wrong step
howler
clanger