Yes, loan is a Scrabble word!
...and is worth 4 points in Scrabble, and 6 points in Words with Friends
loan
Verb
1. Give temporarily; let have for a limited time
Noun
1. The temporary provision of money (usually at interest)
2. A word borrowed from another language; e.g. `blitz' is a German word borrowed into modern English
What Scrabble words can I make with the letters in loan?
2 Letter Words