bad

American Heritage® Dictionary of the English Language, Fourth Edition

1. adj. Not achieving an adequate standard; poor: a bad concert.
2. adj. Evil; sinful.
3. adj. Vulgar or obscene: bad language.
4. adj. Informal Disobedient or naughty: bad children.
5. adj. Disagreeable, unpleasant, or disturbing: a bad piece of news.
6. adj. Unfavorable: bad reviews for the play.
7. adj. Not fresh; rotten or spoiled: bad meat.
8. adj. Injurious in effect; detrimental: bad habits.
9. adj. Not working properly; defective: a bad telephone connection.
10. adj. Full of or exhibiting faults or errors: bad grammar.
11. adj. Having no validity; void: passed bad checks.
12. adj. Being so far behind in repayment as to be considered a loss: bad loans.
13. adj. Severe; intense: a bad cold.
14. adj. Being in poor health or in pain: I feel bad today.
15. adj. Being in poor condition; diseased: bad lungs.
16. adj. Sorry; regretful: She feels bad about how she treated you.
17. adj. Slang Very good; great.
18. n. Something that is below standard or expectations, as of ethics or decency: weighing the good against the bad.
19. adv. Usage Problem Badly.
20. idiom. in bad Informal In trouble or disfavor.
21. idiom. my bad Slang Used to acknowledge that one is at fault.
22. idiom. half Informal Reasonably good.
23. v. Archaic A past tense of bid.

Century Dictionary and Cyclopedia

1. Evil; ill; vicious; wicked; depraved: applied to persons, conduct, character, influence, etc.: as, a bad man; bad conduct; a bad life; a bad heart; bad influence, etc.
2. Offensive; disagreeable; troublesome; painful; grievous: as, bad treatment; a bad temper; it is too bad that you had to wait so long.
3. Hurtful; noxious; having an injurious or unfavorable tendency or effect: with for: as, bad air or bad food; late hours are bad for the health; this step would be bad for your reputation or prospects.
4. Ill; in ill health; sick; in unsound condition: as, to feel bad; to be bad with rheumatism; a bad hand or leg.
5. Not good; defective; worthless; poor; of no value: as, bad coin; bad debts; a bad soil; a bad crop; a bad piece of work; bad health.
6. Incorrect; faulty: as, a bad aim; bad English; a bad pronunciation.
7. Not valid; not sound: as, a bad claim; a bad plea.
8. Unfavorable; unfortunate: as, bad news; bad success.
9. [Bad is the ordinary antithesis of good, in all its senses, whether positively, ‘evil,’ ‘harmful,’ or negatively, ‘not good,’ ‘not satisfactory,’ and whether substantively, ‘being evil,’ or causally, ‘causing harm.’ The senses run into one another, the precise application being determined by the context.]
10. n. That which is bad. A bad condition: as, to go to the bad (see below). A bad thing: as, there are bads and goods among them.
11. n. Preterit of bid.

Wiktionary

1. v. UK, dialect, transitive To shell (a walnut).
2. v. archaic Alternative past tense of bid. See bade.
3. adj. Not good; unfavorable; negative.
4. adj. Seemingly non-appropriate, in manners, etc.
5. adj. Not suitable or fitting.
6. adj. Tricky; stressful; unpleasant.
7. adj. Evil; wicked.
8. adj. Faulty; not functional.
9. adj. of food Spoiled, rotten, overripe.
10. adj. Malodorous, foul.
11. adj. informal Bold and daring.
12. adj. Severe, urgent.
13. adv. Badly.
14. n. slang error, mistake
15. adj. this sense?) (slang) Fantastic.

GNU Webster's 1913

1. obsolete Bade.
2. adj. Wanting good qualities, whether physical or moral; injurious, hurtful, inconvenient, offensive, painful, unfavorable, or defective, either physically or morally; evil; vicious; wicked; -- the opposite of good.

WordNet 3.0

1. adj. feeling or expressing regret or sorrow or a sense of loss over something done or undone
2. adv. with great intensity (`bad' is a nonstandard variant for `badly')
3. adj. having undesirable or negative qualities
4. adj. physically unsound or diseased
5. adj. capable of harming
6. adj. (of foodstuffs) not in an edible or usable condition
7. adj. characterized by wickedness or immorality
8. adj. not capable of being collected
9. adj. reproduced fraudulently
10. adj. not financially safe or secure
11. n. that which is below standard or expectations as of ethics or decency
12. adj. nonstandard.
13. adj. very intense
14. adj. below average in quality or performance
15. adj. feeling physical discomfort or pain (`tough' is occasionally used colloquially for `bad')
16. adj. not working properly
17. adv. very much; strongly.