a jam session meaning

• [American slang]
  an informal session where musicians play together.
    Andy and Nick had a jam session last night and kept all the neighbors awake.

• The audience doesn't just want to hear a jam session.
• The visit turned into a jam session involving musicians from several bands.
• It's almost like music, a jam session.
• After the chairs were cleared, a jam session began.
• When we got back, someone suggested a jam session.
• You can play alone or have a jam session with your friends,
• He participated in a jam session and radio performance with Louis Armstrong.
• McLaughlin recollects " we played one night, just a jam session.
• Adler and Sabatino met at a jam session in New York City.
• Freeman still leads a jam session at his regular weekly show in Chicago.

• "a jam session" meaning in Japanese: 《口語》 即興ジャズ演奏会, ジャムセッション