Yes, prime is a Scrabble word!

Verb

1. Insert a primer into (a gun, mine, or charge) preparatory to detonation or firing

2. Cover with a primer; apply a primer to

3. Fill with priming liquid

Adjective

1. First in rank or degree

2. Used of the first or originating agent

3. Of superior grade

4. Of or relating to or being an integer that cannot be factored into other integers

5. Being at the best stage of development

Noun

1. A number that has no factor but itself and 1

2. The period of greatest prosperity or productivity

3. The second canonical hour; about 6 a.m.

4. The time of maturity when power and vigor are greatest