spontaneous

adjective

1. 1

   Self-generated; happening without any apparent external cause.

   “He made a spontaneous offer of help.”

2. 2

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

3. 3

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

4. 4

   Arising from a momentary impulse

5. 5

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

6. 6

   Produced without being planted or without human cultivation or labor.

7. 7

   Random.

8. 8

   Sudden, without warning.