Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
nonvoluntary is an adjective meaning "not subject to the control of the will". It carries one recorded sense.
not subject to the control of the will
“involuntary manslaughter”
“involuntary servitude”
“an involuntary shudder”
“It (becoming a hero) was involuntary. They sank my boat”
Definitions, synonyms and semantic relations for nonvoluntary come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.