Yes, jam is a Scrabble word!

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