These words denote something done, said or believed incorrectly or improperly. Mistake and error are the most common and general words of this group. In many contexts they are interchangeable, but error often implies deviation from a standard or model, whereas mistake is preferred in the common situations of everyday life.

• It was a mistake to suppose that George could ever get here on time; an error in logic or in arithmetic; a typographical error.

Error is used also in a theological sense to mean sin, since sin is perceived as deviation from the moral standards or theological truth established by religion.

A blunder is a blatant error , usually one involving behaviour or judgement, and implying an ignorant or uninformed assessment of a situation.

• Offering to negotiate with the enemy at that time was an inexcusable blunder .

Slip and faux pas (literally "false step ") are minor mistakes . Slip emphasizes the accidental rather than ignorant character of a mistake and is often used to mean the careless divulging of secret or private information: a slip of the tongue. A faux pas is an embarrassing beach of etiquette.

• He forgot that she had remarried, and introduced her with her first husband’s name – a faux pas that made everybody momentarily uncomfortable.

Boner , boo-boo and goof are all slang terms, and all have a somewhat humorous tone. A boo-boo or a boner is any egregious and mindless mistake : He made a real boner when he invited the Hindu home to a dinner of roast beef. Boo-boo is more good humouredly accepted as a minor faux pas of slip of the tongue: one boo-boo after another as she introduced her guests. Similarly, a goof is an indefensible but honestly admitted error which contains in its admission a covert plea that the goof be regarded with indulgent forgiveness.

• We really goofed this time, didn’t we?

A contretemps , literally "counter to or against the time," i.e., at the wrong time, refers to an embarrassing or awkward occurrence. The young girl who puts off a too-ardent admirer by saying she is quite ill, and then encounters him that very night at a party, has learnt the meaning of contretemps in a way that she is not likely to forget.