Yes, deaden is a Scrabble word!

Verb

1. Make vague or obscure or make (an image) less visible

2. Cut a girdle around so as to kill by interrupting the circulation of water and nutrients

3. Make vapid or deprive of spirit

4. Lessen the momentum or velocity of

5. Become lifeless, less lively, intense, or active; lose life, force, or vigor

6. Make less lively, intense, or vigorous; impair in vigor, force, activity, or sensation

7. Convert (metallic mercury) into a grey powder consisting of minute globules, as by shaking with chalk or fatty oil