mad money noun2 •A sum of money, often relatively small in amount, kept in reserve to use for impulsive, frivolous purposes.Ultrasuede minibags "are just the solution for waste." And for crime. Most minis hardly hold more than mad money and a comb. — 1975 •A sum of money kept in reserve or to insulate oneself financially in the event of the sudden breakdown of a relationship in which one is economically dependent.
