Yes, cuss is a Scrabble word!
...and is worth 6 points in Scrabble, and 8 points in Words with Friends
cuss
Verb
1. Utter obscenities or profanities
Noun
1. A persistently annoying person
2. A boy or man
3. Profane or obscene expression usually of surprise or anger
What Scrabble words can I make with the letters in cuss?
2 Letter Words