Definition of "earthnut"

Any of various roots, tubers, or pods that grow underground.

1. A tuber belonging to the species Conopodium majus (syns. Bunium flexuosum, Conopodium denudatum), Bunium bulbocastanum (syn. Carum bulbocastanum), or Apios americana (syn. Apios tuberosa)  examples

2. The dwarf ginseng: Panax trifolius  examples

3. Synonym of peanut (Arachis hypogaea)  examples

4. The underground tuber belonging to the genus Tuber; the truffle.  examples