Untrained rhymes with:
constrained, restrained, retrained, strained, trained, unconstrained, unrestrained, brained, constrained, craned, drained, grained, ingrained, rained, refrained, reigned, reined, restrained, retrained, sprained, strained, trained, unconstrained, unrestrained
Untrained sounds like:
unadorned, underhanded, undermanned, undermined, underneath, underwent, undetermined, undreamed, unturned