noun

• (less common in the US and Canada) A sweet mixture of fruit boiled with sugar and allowed to congeal. Often spread on bread or toast or used in jam tarts
  "He is allergic to jam."
• (countable) A difficult situation.
  "It's a blackmail ring, and the district attorneys get a share of the loot. […] Well, they got him in the same kind of jam, and soaked him to the tune of three hundred and eighty-six thousand."
• (countable) A difficult situation.
  "The pitcher's in a jam now, having walked the bases loaded with the cleanup hitter coming to bat."
• (countable) A blockage, congestion, or immobilization.
  "a jam on the 101 South, blocking the two right lanes [radio report]"

verb

• (baseball) To throw a pitch at or near the batter's hands.
  "Jones was jammed by the pitch."
• (basketball) To dunk.
• (music) To play music (especially improvisation as a group, or an informal unrehearsed session).
• (roller derby) To attempt to score points.
  "Toughie jammed four times in the second period."

noun

• (dated) A kind of frock for children.

noun

• (mining) Alternative form of jamb.