Yes, ill is a Scrabble word!
...and is worth 3 points in Scrabble, and 5 points in Words with Friends
ill
Adverb
1. (`ill' is often used as a combining form) in a poor or improper or unsatisfactory manner; not well
2. Unfavorably or with disapproval
3. With difficulty or inconvenience; scarcely or hardly
Adjective
1. Affected by an impairment of normal physical or mental function
2. Resulting in suffering or adversity
3. Distressing
4. Indicating hostility or enmity
5. Presaging ill fortune
Noun
1. An often persistent bodily disorder or disease; a cause for complaining
What Scrabble words can I make with the letters in ill?
2 Letter Words