blunder

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A usually serious mistake typically caused by ignorance or confusion.
2. v. To move clumsily or blindly.
3. v. To make a usually serious mistake.
4. v. To make a stupid, usually serious error in; botch.
5. v. To utter (something) stupidly or thoughtlessly.

Century Dictionary and Cyclopedia

1. To move or act blindly, stupidly, or without direction or steady guidance; flounder; stumble: frequently with on or along.
2. To make a gross mistake, especially through mental confusion; err widely or stupidly.
3. To mix (things) confusedly; confuse.
4. To confound; confuse; distract; cause to make blunders: as, “to blunder an adversary,”
5. To injure or destroy by blundering; mismanage: as, “to darken or blunder the cause,”
6. To do or make faultily or erroneously; make mistakes in through ignorance or stupidity; bungle.
7. To utter thoughtlessly or in a blundering manner; blurt out: generally with out: as, to blunder out an excuse.
8. n. A mistake made through precipitance or mental confusion; a gross or stupid mistake.
9. n. Synonyms Error, Mistake, Blunder, Bull. An error is a wandering from truth, primarily in impression, judgment, or calculation, and, by extension of the idea, in conduct; it may be a state. A mistake is a false judgment or choice; it does not, as error sometimes does, imply moral obliquity, the defect being placed wholly in the wisdom of the actor, and in its treatment of this defect the word is altogether gentle. Blunder is a strong word for a mistake which is stupid, a gross error in action or speech. A bull is a blunder in language, involving generally a very obvious and comical contradiction; but the word is sometimes applied to any particularly inapt or ludicrously inappropriate remark.

Wiktionary

1. n. A clumsy or embarrassing mistake.
2. v. To make a stupid mistake.
3. v. To move blindly or clumsily.

GNU Webster's 1913

1. v. To make a gross error or mistake.
2. v. To move in an awkward, clumsy manner; to flounder and stumble.
3. v. To cause to blunder.
4. v. To do or treat in a blundering manner; to confuse.
5. n. Confusion; disturbance.
6. n. A gross error or mistake, resulting from carelessness, stupidity, or culpable ignorance.

WordNet 3.0

1. v. make one's way clumsily or blindly
2. v. commit a faux pas or a fault or make a serious mistake
3. v. utter impulsively
4. n. an embarrassing mistake