Entry 1 sense Webster, 1913 Groundnut /(ground"nŭt`)/ · Ground·nut · IPA /ɡrˈaʊndnˌʌt/ 01 n. The fruit of the Arachis hypogæa (native country uncertain); the peanut; the earthnut. 1. The fruit of the Arachis hypogæa (native country uncertain); the peanut; the earthnut.(Bot.) [U. S.]