Yes, loud is a Scrabble word!
...and is worth 5 points in Scrabble, and 7 points in Words with Friends
loud
Adverb
1. With relatively high volume
Adjective
1. Characterized by or producing sound of great volume or intensity
2. Tastelessly showy
3. Used chiefly as a direction or description in music
What Scrabble words can I make with the letters in loud?
3 Letter Words
2 Letter Words