Nest Egg Meaning

(idiomatic) A savings; a reserve of money.

Example: A natural or artificial egg placed in a bird's nest, to encourage the bird to lay its own eggs there.
Patent No. 211,363 was issued on Jan. 14, 1879 to O. F. Woodward for a Nest-Egg:
  My improvement relates to artificial eggs composed of a substance which is offensive to insects, the object being to render the same effective, not only as a nest-egg, but also as a destroyer of vermin.
  Over time, they accumulated a tidy nest egg and retired comfortably.
1915, W.S. Maugham, "Of Human Bondage":
  When Mrs. Carey was married she had three hundred pounds, and this money, carefully watched, had been used by her to meet any unforeseen expense, any urgent charity, or to buy Christmas and birthday presents for her husband and for Philip. In the course of years it had diminished sadly, but it was still with the Vicar a subject for jesting. He talked of his wife as a rich woman and he constantly spoke of the "nest egg".
An egg squash.