IPA: //nɒnˈnætʃərəl//
KK: /nɑnˈnætʃərəl/
Something that is not found in nature or is artificial.
The scientist studied the effects of nonnatural substances on the environment.
Nonnatural → It is formed from "non-" (meaning not) and "natural" (from Latin "naturalis", meaning of nature). The word "nonnatural" means not of nature or not occurring naturally.
Think of 'non-' meaning 'not' and 'natural' relating to nature — so nonnatural refers to something that is not natural.