means A small compact lump of something, especially gold or food, that packs value or substance into a tiny size.

from English seems to have minted 'nugget' in the early 19th century, right around the gold rushes that gave the word its glitter. It's likely a tweak of the dialect word 'nug,' meaning a lump or chunk — possibly tied to an older sense of 'nug' as a small, thick thing. The exact root is murky, but the image is solid: something little and dense and worth grabbing.