what is lump
Definition of lump. 1  transitive verb. 2  1 : to group indiscriminately. 3  2 : to make into lumps; also : to make lumps on or in. 4  3 : to move noisily and clumsily. 5  intransitive verb. 6  1 : to become formed into lumps. 7  2 : to move oneself noisily and clumsily.