Meaning

• Self-generated; happening without any apparent external cause.

  "He made a spontaneous offer of help."

• Done by one's own free choice, or without planning.

• Proceeding from natural feeling or native tendency without external or conscious constraint

• Arising from a momentary impulse

• Controlled and directed internally; self-active; spontaneous movement characteristic of living things

• Produced without being planted or without human cultivation or labor.

• Random.

• Sudden, without warning.