To secrete, hoard, or store something away so as to avoid discovery by others or to preserve or amass for future use. A noun or pronoun can be used between "stash" and "away." Please, you have to stash these drugs away for me. The cops won't look in your house! My wife stashes chocolates away in the back of the cupboard like she's trying to hide them from me or something. My grandmother stashed away a bit of money every week under her mattress until she and my grandfather retired.