IPA: /əˈtʃiːvər/
KK: /əˈtʃivər/
A person who successfully reaches their goals or accomplishments, often recognized for their success.
She is an achiever who has won several awards for her contributions to science.
Achiever is formed from "achieve" (from Old French *achever*, meaning to complete or finish) and "-er" (meaning a person who). An achiever is a person who completes or accomplishes something.
Think of someone who 'completes' something ('achieve') — the '-er' just means a person. An achiever is someone who gets things done.