Yes, bad is a Scrabble word!
...and is worth 6 points in Scrabble, and 7 points in Words with Friends
bad
Adverb
1. With great intensity (`bad' is a nonstandard variant for `badly')
2. Very much; strongly
Adjective
1. Having undesirable or negative qualities
2. Very intense
3. Feeling physical discomfort or pain (`tough' is occasionally used colloquially for `bad')
4. (of foodstuffs) not in an edible or usable condition
5. Feeling or expressing regret or sorrow or a sense of loss over something done or undone
6. Not capable of being collected
7. Below average in quality or performance
8. Nonstandard
9. Not financially safe or secure
10. Physically unsound or diseased
11. Capable of harming
12. Characterized by wickedness or immorality
13. Reproduced fraudulently
14. Not working properly
Noun
1. That which is below standard or expectations as of ethics or decency
What Scrabble words can I make with the letters in bad?
3 Letter Words
2 Letter Words