Underlining rhymes with:
headlining, outlining, redlining, streamlining, headlining, intertwining, outlining, outshining, redlining, streamlining, undermining
Underlining sounds like:
underlines, underling, underlings, underlying
headlining, outlining, redlining, streamlining, headlining, intertwining, outlining, outshining, redlining, streamlining, undermining
underlines, underling, underlings, underlying