IPA: /əˈkɒmplɪʃə/
KK: /əˈkɑmplɪʃər/
A person who successfully completes a task or achieves a goal.
She is an accomplisher of many great projects in her career.
Accomplisher is formed from "accompli" (from Old French *accomplir*, meaning to fulfill or complete) and "-er" (meaning a person who). The word refers to a person who fulfills or completes a task or goal.
Think of someone who 'fulfills' or 'completes' something — that's what an accomplisher does.