IPA: //ədˈhɪrər//
KK: /ædˈhɪrər/
A person who supports or follows a particular belief, idea, or leader.
As an adherer of the philosophy, she attended every meeting and discussion.
Adherer is formed from "ad-" (meaning to) and "haerere" (meaning to stick or cling). The word describes someone who sticks to or clings to a belief, principle, or cause.
Think of someone who 'sticks to' ('haerere') something they believe in, as 'ad-' means to, making an adherer someone who is committed.