slub1 Syllabification: (slub)Pronunciation: /sləb/Definition of slub noun a lump or thick place in yarn or thread. fabric woven from yarn or thread containing lumps or thick spots. adjective [attributive] (of fabric) having an irregular appearance caused by uneven thickness of the warp. Derivatives slubbed adjective Origin: early 19th century: of unknown originslub in other Oxford dictionaries Definition of slub in the British & World English dictionary