Nugget definition: A nugget is a small lump of something, especially gold. | Meaning, pronunciation, translations and examples. a lump of gold as found in gold mining or digging; - called also a pepito. See also: Gold. Webster's Revised Unabridged Dictionary, published by C. & G. I define a golden nugget as the most important lesson, but everyone has their own definition. I've heard it called key takeaway, lesson learned, words of wisdom.