Jam \Jam\, v. t. [imp. & p. p. Jammed; p. pr. & vb. n. Jamming.]

[Either fr. jamb, as if squeezed between jambs, or more likely from the same source as champ See Champ.]

1. To press into a close or tight position; to crowd; to squeeze; to wedge in.

The . . . jammed in between two rocks. --De Foe.

2. To crush or bruise; as, to jam a finger in the crack of a door. [Colloq.]

3. (Naut.) To bring (a vessel) so close to the wind that half her upper sails are laid aback. --W. C. Russell.

Source: Webster's Revised Unabridged Dictionary (1913)