IPA: /dɪsˈbiːlɪvə/
KK: /dɪsˈbilɪvər/
A person who does not accept or believe in something, especially a particular belief or idea.
As a disbeliever in the theory, she often questioned its validity.
Disbeliever → It is formed from "dis-" (meaning apart or not) and "believe" (from Old English "beliefe", meaning to hold as true). The word "disbeliever" refers to someone who does not hold something as true or has rejected a belief.
Think of someone who is 'not' ('dis-') accepting something as true ('believe'). This helps you remember that a disbeliever is someone who does not believe.