Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
nonnatural is an adjective meaning "existing outside of or not in accordance with nature". It carries one recorded sense.
existing outside of or not in accordance with nature
“find transcendental motives for sublunary action”
Definitions, synonyms and semantic relations for nonnatural come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.