eager beaver

[ee-ger]

noun

1. a person who is excessively diligent or overly zealous.

eager beaver

noun

1. informal,  a person who displays conspicuous diligence, esp one who volunteers for extra work

Word History and Origins

Origin of eager beaver¹

An Americanism dating back to 1940–45

Idioms and Phrases

An exceptionally zealous person, one who habitually takes on more tasks or works harder than others. For example, Bill is a real eager beaver, always volunteering to stay late. This expression became especially popular during World War II, applied to recruits anxious to impress their commanding officers by such behavior. [First half of 1900s]