lumpyPronunciation: /ˈlʌmpi/Translate lumpy | into German | into Italian | into Spanish Definition of lumpy adjective (lumpier, lumpiest) full of or covered with lumps:he lay on the lumpy mattress Nautical (of water) formed by the wind into small waves:there’s a lumpy sea runningDerivatives lumpily adverb lumpiness noun lumpy in other Oxford dictionaries Definition of lumpy in the US English dictionary