IPA: /ˈaɪdəˌleɪtər/
KK: /ˈaɪdələtər/
A person who shows extreme admiration or devotion to someone or something, often to the point of worship.
Many fans become idolaters of their favorite celebrities, following their every move.
Idolater is formed from "idolum" (meaning an image or representation) and "-ater" (a suffix indicating a person who performs an action). The word refers to a person who worships an idol or image, emphasizing the act of idol worship.
Think of someone who is devoted to an 'image' ('idolum') — that's why an idolater is a person who worships an idol.