Yes, longer is a Scrabble word!

Adverb

1. For more time

Adjective

1. Primarily temporal sense; being or indicating a relatively great or greater than average duration or passage of time or a duration as specified

2. Primarily spatial sense; of relatively great or greater than average spatial extension or extension as specified

3. Of relatively great height

4. Good at remembering

5. Holding securities or commodities in expectation of a rise in prices

6. (of speech sounds or syllables) of relatively long duration

7. Involving substantial risk

8. Planning prudently for the future

9. Having or being more than normal or necessary:"long on brains"

Noun

1. A person with a strong desire for something