/inˈvälənˌterē/
Adjective
1. One that occurs without volition or will. (wikipedia.org)
2. Done without conscious control. (Google Dictionary)
3. Without intention; unintentional. (wiktionary.org)
4. (esp. of muscles or nerves) Concerned in bodily processes that are not under the control of the will. (Google Dictionary)
5. Controlled by the autonomic nervous system; without conscious control. (wordnetweb.princeton.edu)
Word origin: From Late Latin involuntarius “involuntary,” from in– “not, opposite of”