Of low quality.

Inaccurate; incorrect

Unfavorable; negative; not good.

Not suitable or fitting.

Not appropriate, of manners etc.

Harmful, especially unhealthy; liable to cause health problems.

(chiefly applied to a person's state of health) Sickly, unhealthy, unwell.

The injured or weak one of a pair of body parts, where the other one is healthy.

(often childish) Not behaving; behaving badly; misbehaving; mischievous or disobedient.

Tricky; stressful; unpleasant.

(sometimes childish) Evil; wicked.

Faulty; not functional.

(of food) Spoiled, rotten, overripe.

(of breath) Malodorous; foul.

False; counterfeit; illegitimate.

Unskilled; of limited ability; not good.

Of poor physical appearance.

(of a need, want, or pain) Severe, urgent.

(preceded by feel) Regretful, guilty, or ashamed.

(of a word, speech, or writing) Vulgar, obscene, or blasphemous.

Not worth it.

(informal, of a draft/check) Not covered by funds on account.

Bold, daring, and tough.

(semantic change, amelioration, contranymic) Good, superlative, excellent, cool.

(US) Overly promiscuous, licentious.

(originally African-American Vernacular, of a woman) Very attractive; hot, sexy.

(Internet slang, sarcastic) Used without a copula to mock people who oppose something without having any real understanding of it.

(chiefly in "bad boy", "bad girl", and similar phrases) Attractive due to (one's) rebellious nature.

(now colloquial) Badly; poorly.

(intensifier) Badly; severely, extremely, passionately, eagerly.

Something that is bad; a harm or evil.

(slang, with possessive determiner) Error; mistake.

(countable, uncountable, economics) An item (or kind of item) of merchandise with negative value; an unwanted good.

Used to scold a misbehaving child or pet.

(archaic) alternative past of bid. See bade.

(British, dialect, transitive) To shell (a walnut).