Meaning

noun any of various highly prized edible subterranean fungi of the genus Tuber; grow naturally in southwestern Europe

noun a common European plant having edible tubers with the flavor of roasted chestnuts

noun pod of the peanut vine containing usually 2 nuts or seeds; `groundnut' and `monkey nut' are British terms

originInherited from Middle English erthenote, from Old English eorþhnutu, from Proto-Germanic *erþōhnuts; equivalent to earth + nut.

Etymology from Wiktionary, CC BY-SA 3.0