spontaneous

adj

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

   “He made a spontaneous offer of help.”

   “To make a spontaneous decision”

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

   “YSL, as he is often called, is equally capable of casual, aristocratic cruelty and earthy, spontaneous tenderness, and when you study his face it can be hard to distinguish boredom from rapture.”

3. Proceeding from natural feeling or native tendency without external or conscious constraint.
4. Arising from a momentary impulse.
5. Controlled and directed internally; self-active; spontaneous movement characteristic of living things.
6. Produced without being planted or without human cultivation or labor.

   “He persisted in his design; and, because he would not make his wants known, actually subsisted for several days on hips, haws and sloes, and other spontaneous fruits which he gathered in the woods and fields.”

7. Sudden, without warning.
8. Said or done without prior planning or prior writing.

   “He made a spontaneous remarks in the court.”