A jamb is a post that forms the side of a door or window. A jam is (1) a preserve made from boiled and sugared fruit, (2) a congestion, (3) a difficult situation, and (4) a song that one holds to be especially moving or meaningful. The word also works as a verb in several senses, including (1) to drive or wedge into a tight position, (2) to lock into an unworkable position, and (3) to cram.
Examples
Jamb
Damages to the door and door jamb were estimated at $1,000. [Peabody Gazette-Bulletin]
There it was, a back door that had been kicked in, the lock unmoored from the door jamb, the jamb’s wood in splinters. [Chicago Tribune]
Jam
But Force says he was in Victoria on Thursday morning, nowhere near the traffic jam south of Vancouver. [CBC]
There was homemade “rhuberry” (rhubarb and strawberry) jam at breakfast. [Guardian]
But as she reached into the machine to remove a jammed clip, she accidentally pressed down on the machine’s foot pedal. [New Zealand Herald]