underˈsearch,v.rare. [under-1 4 a, b, 8 a.] To search or seek under or into; to investigate. 1609Daniel Civ. Wars iii. iv, Whil'st th' vnder-searching water, working-on, Beares (proudly) downe, all that was idly don.1648Hexham ii, Ondertasten, to Examine, or Vndersearch.