Sudden, without warning.
Controlled and directed internally; self-active; spontaneous movement characteristic of living things.
Random.
Done by one's own free choice, or without planning.
Produced without being planted or without human cultivation or labor.
Arising from a momentary impulse.
Self-generated; happening without any apparent external cause.
Proceeding from natural feeling or native tendency without external or conscious constraint.
Not willed or wished for.
Not disposed of in a legal will.