IPA: /ʌnˈnætʃərəli/
KK: /ʌnˈnætʃərəli/
In a way that is not natural or normal; often artificial or forced.
The actor spoke unnaturally, making it hard to believe his character.
Unnaturally → It is formed from "un-" (meaning not) and "natural" (from Latin "naturalis", meaning pertaining to nature) and the suffix "-ly" (meaning in a manner). The word "unnaturally" means in a manner that is not natural or contrary to nature.
Think of 'not' ('un-') being added to 'natural' to remember that 'unnaturally' means something that is not in its natural state.