Underlying rhymes with:
overlying, applying, belying, complying, flying, implying, lying, misapplying, overflying, overlying, plying, relying, replying, supplying
Underlying sounds like:
underlines, underling, underlings, underlining
overlying, applying, belying, complying, flying, implying, lying, misapplying, overflying, overlying, plying, relying, replying, supplying
underlines, underling, underlings, underlining