lightsPronunciation: /lʌɪts/Definition of lights noun the lungs of sheep, pigs, or bullocks, used as food, especially for pets. Phrases punch someone's lights out beat someone up: the last time he called me that, I’d attempted to punch his lights outOrigin: Middle English: use of light2 as a noun (so named because of their lightness). Compare with lunglights in other Oxford dictionaries Definition of lights in the US English dictionary