Read the dictionary definition of bad. All definitions for this word.
1. that which is below standard or expectations as of ethics or decency
1. take the bad with the good
2. feeling physical discomfort or pain (`tough' is occasionally used colloquially for `bad')
1. my throat feels bad
2. she felt bad all over
3. he was feeling tough after a restless night
3. (of foodstuffs) not in an edible or usable condition
1. bad meat
2. a refrigerator full of spoilt food
4. not working properly
1. a bad telephone connection
2. a defective appliance
5. reproduced fraudulently
1. like a bad penny...
2. a forged twenty dollar bill
6. having undesirable or negative qualities
1. a bad report card
2. his sloppy appearance made a bad impression
3. a bad little boy
4. clothes in bad shape
5. a bad cut
6. bad luck
7. the news was very bad
8. the reviews were bad
9. the pay is bad
10. it was a bad light for reading
11. the movie was a bad choice
7. characterized by wickedness or immorality
1. led a very bad life
8. feeling or expressing regret or sorrow or a sense of loss over something done or undone
1. felt regretful over his vanished youth
2. regretful over mistakes she had made
3. he felt bad about breaking the vase
9. capable of harming
1. bad air
2. smoking is bad for you
10. physically unsound or diseased
1. has a bad back
2. a bad heart
3. bad teeth
4. an unsound limb
5. unsound teeth
11. very intense
1. a bad headache
2. in a big rage
3. had a big (or bad) shock
4. a bad earthquake
5. a bad storm
12. not financially safe or secure
1. a bad investment
2. high risk investments
3. anything that promises to pay too much can't help being risky
4. speculative business enterprises
13. nonstandard
1. so-called bad grammar
14. below average in quality or performance
1. a bad chess player
2. a bad recital
15. not capable of being collected
1. a bad (or uncollectible) debt
16. very much; strongly
1. I wanted it badly enough to work hard for it
2. the cables had sagged badly
3. they were badly in need of help
4. he wants a bicycle so bad he can taste it
17. with great intensity (`bad' is a nonstandard variant for `badly')
1. the injury hurt badly
2. the buildings were badly shaken
3. it hurts bad
4. we need water bad