IPA: /əˈtækər/
KK: /əˈtækər/
A person who initiates an attack or assault on someone or something.
The attacker was apprehended by the police shortly after the incident.
Attacker → It is formed from "attack" (from Old French *ataquer*, meaning to assault or set upon) and "-er" (meaning a person who). An attacker is a person who assaults or sets upon someone or something.
Think of someone who 'assaults' ('attack') another person — the '-er' just means a person. An attacker is someone who sets upon another.