Monk, Thelonious Syllabification: (Monk, Thelonious)Pronunciation: /məNGk/Definition of Monk, Thelonious (1917–82), US jazz pianist and composer; a founder of the bebop style in the early 1940s; full name Thelonious Sphere Monk. Notable compositions: “Round Midnight,” “Straight, No Chaser,” and “Well, You Need.n’t”. Monk, Thelonious in other Oxford dictionaries Definition of Monk, Thelonious in the British & World English dictionary