- The definition of a no brainer is a situation in which there is one clear obvious or right answer and in which no real thought is required to decide what to do.
An example of a no brainer is if someone asks if you want a million dollars free and clear with absolutely no taxes or strings attached.
no-brainer definition by Webster's New World
no-brainer definition by American Heritage Dictionary
no-brainer - Cultural Definition
Something that is absurdly simple or easy and requires little thought: “Making pumpkin pie can be a no-brainer if you use frozen pastry and canned filling.”