What is the meaning of the word "eager beaver"?

Definitions:

  1. A person who is extremely zealous about performing duties and volunteering for more. copy to clipboard NOUN
    • Mary is such an eager beaver- she is always the first one to do whatever the boss asks. copy to clipboard
  2. A person who is willing to work very hard. copy to clipboard NOUN
    • She's an eager beaver, always the first to arrive and the last to leave, ensuring every project exceeds expectations. copy to clipboard
  3. Someone who is very enthusiastic about doing something and is very hard-working. copy to clipboard NOUN
    • My little sister is such an eager beaver that she has packed a massive suitcase to go on her first school trip, even though it is only for two days. copy to clipboard

Synonyms: