Dimetapp rhymes with:
wiretap, ascap, automap, backslap, belnap, bootstrap, burlap, catnap, corcap, flytrap, handicap, hubcap, kidnap, kneecap, lightcap, madcap, midcap, millsap, milsap, mishap, mousetrap, overlap, realcap, recap, roadcap, rocap, skycap, smallcap, stopgap, westcap, wiretap, yonhap
Dimetapp sounds like:
dehumidify, diminutive, dinotopia