Source : WordNet®

wing nut
     n 1: any tree of the genus Pterocarya; fruit is a small winged
          nutlet; Caucasus to southeastern Asia [syn: {wing-nut}]
     2: a threaded nut with winglike projections for thumb and
        forefinger leverage in turning [syn: {wing-nut}, {wing
        screw}, {butterfly nut}, {thumbnut}]