Yes, lower is a Scrabble word!

Verb

1. Move something or somebody to a lower position

2. Set lower

3. Make lower or quieter

4. Cause to drop or sink

5. Look angry or sullen, wrinkle one's forehead, as if to signal disapproval

Adjective

1. Less than normal in degree or intensity or amount

2. Literal meanings; being at or having a relatively small elevation or upward extension

3. Very low in volume

4. Unrefined in character

5. Used of sounds and voices; low in pitch or frequency

6. Of the most contemptible kind

7. Low or inferior in station or quality

8. No longer sufficient

9. Subdued or brought low in condition or status

10. Filled with melancholy and despondency

Noun

1. The lower of two berths