money saved and held in reserve for emergencies, retirement, etc.

a natural or artificial egg placed in a nest to induce a hen to continue laying eggs there.

noun

backup , cache , emergency funds , funds , investment , life savings , mad money * , means , money in the bank , piggy bank , provisions , rainy day fund , reserve , reserve fund , reserves , resources , savings , savings account , sinking fund , something for a rainy day , something to fall back on , stash , stockpile , unexpended balance , backlog , inventory , reservoir , stock , store , treasure