1. A container for transporting meals, especially lunch.
2. (slang) A person or object constantly at one's side (in the manner of a lunchbox).
3. (British slang) The male genitals when enclosed in clothing.
4. (Asia) A to-go lunch packaged in a disposable box.
5. (computing, slang) A luggable; an early laptop computer, usually a unit with a handle and a fold-out keyboard.