'nest egg' definitions:

Definition of 'nest egg'

From: WordNet
noun
A fund of money put by as a reserve [syn: savings, nest egg]
noun
Device consisting of an artificial egg left in a nest to induce hens to lay their eggs in it

Definition of 'nest egg'

From: GCIDE
  • nest egg \nest egg\, n.
  • 1. An egg left in the nest to prevent the hen from forsaking it, and to induce her to lay more in the same place. [1913 Webster]
  • 2. Hence, (figuratively), Money set aside in a special fund to be used for special occasions, or more commonly, for retirement; as, she set aside a large hunk of her salary every month and had a considerable nest egg for her retirement. [PJC]

Synonyms of 'nest egg'

From: Moby Thesaurus