Yes, roar is a Scrabble word!

Verb

1. Make a loud noise, as of wind, water, or vehicles

2. Utter words loudly and forcefully

3. Emit long loud cries

4. Act or proceed in a riotous, turbulent, or disorderly way

5. Make a loud noise, as of animal

6. Laugh unrestrainedly and heartily

Noun

1. A deep prolonged loud noise

2. A very loud utterance (like the sound of an animal)

3. The sound made by a lion