IPA: /ˌoʊvərˈriːtʃər/
KK: /oʊvərˈriːtʃər/
A person who tries to achieve more than is reasonable or possible, often leading to failure or disappointment.
The overreacher attempted to take on too many responsibilities at work, which caused him stress.
Overreacher → It is formed from "over-" (meaning excessively or beyond) and "reach" (from Old English "ræcan", meaning to stretch out or extend). The word "overreacher" describes someone who excessively stretches their ambitions or efforts beyond reasonable limits.
Think of someone who goes 'beyond' ('over-') their ability to 'reach' for something — that's why an overreacher is someone who tries to achieve too much.
No commonly confused words.