Underpin rhymes with:
kingpin, linchpin, tailspin, underspin, alperin, amylin, bergin, bogeymen, buckskin, bushkin, crooklyn, dechine, deerskin, drabkin, foreskin, goodkin, goodwyn, grandin, has-been, jocelin, joceline, jocelyn, jocelyne, josleyn, joycelyn, katyn, kingpin, linchpin, mandolin, medecin, might-have-been, myojin, pigskin, puffin, redskin, rosalynn, sandin, sheepskin, shokhin, solwin, solzhenitsyn, sosin, southin, tailspin, towbin, underspin, unitrin, waitzkin, wildasin, witkin