Yes, jam is a Scrabble word!
...and is worth 12 points in Scrabble, and 15 points in Words with Friends
jam
Verb
1. Press tightly together or cram
2. Push down forcibly
3. Crush or bruise
4. Interfere with or prevent the reception of signals
5. Get stuck and immobilized
6. Crowd or pack to capacity
7. Block passage through
Noun
1. Preserve of crushed fruit
2. Informal terms for a difficult situation
3. A dense crowd of people
4. Deliberate radiation or reflection of electromagnetic energy for the purpose of disrupting enemy use of electronic devices or systems
What Scrabble words can I make with the letters in jam?
2 Letter Words