Yes, firm is a Scrabble word!

Adverb

1. With resolute determination

Verb

1. Become taut or tauter

2. Make taut or tauter

Adjective

1. Marked by firm determination or resolution; not shakable

2. Not soft or yielding to pressure

3. Strong and sure

4. Not subject to revision or change

5. (of especially a person's physical features) not shaking or trembling

6. Not liable to fluctuate or especially to fall

7. Securely established

8. Possessing the tone and resiliency of healthy tissue

9. Securely fixed in place

10. Unwavering in devotion to friend or vow or cause

Noun

1. The members of a business organization that owns or operates one or more establishments