Hidden Reserve is a term used to describe a secret or concealed reserve of something, such as money, resources, or supplies. It is often used in the context of emergency preparedness and financial planning. The two crossword solutions for this term are STASH and CACHE. STASH is defined as a hidden store of something, while CACHE is defined as a collection of items stored away in a hidden or secure place. Both words can be used to refer to a Hidden Reserve.