late 14c. paunce, "the human belly," from Old French pance (Old North French panche) "belly, stomach," from Latin panticem (nominative pantex) "belly, bowels" (source also of Spanish panza, Italian pancia); which is possibly related to panus "swelling" (see panic (n.2)). Earlier in English it meant "plate or mail armor worn to protect the belly" (early 14c.).
adjective suffix, "full of or characterized by," from Old English -ig, from Proto-Germanic *-iga- (source also of Dutch, Danish, German -ig, Gothic -egs), from PIE -(i)ko-, adjectival suffix, cognate with elements in Greek -ikos, Latin -icus (see -ic). Originally added to nouns in Old English; used from 13c. with verbs, and by 15c. even with other adjectives (for example crispy).
<a href="https://www.etymonline.com/word/paunchy">Etymology of paunchy by etymonline</a>
Harper, D. (n.d.). Etymology of paunchy. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/paunchy