Definition of "Jam" :

noun: deliberate radiation or reflection of electromagnetic energy for the purpose of disrupting enemy use of electronic devices or systems

noun: preserve of crushed fruit

noun: a dense crowd of people

noun: informal terms for a difficult situation

verb: interfere with or prevent the reception of signals

"Jam the Voice of America."

verb: block passage through

verb: crush or bruise

"Jam a toe."

verb: crowd or pack to capacity

"The theater was jampacked."

verb: get stuck and immobilized

"The mechanism jammed."

verb: push down forcibly

"The driver jammed the brake pedal to the floor."

verb: press tightly together or cram