Jumbo is unique in the corpus of English place-names. Its etymology and meaning are discused, and an attempt is made to determine if it is exotic or indigenous. Jumbo is places within a family of jumb-root toponyms, whose geographical distribution is defined, and compared to that of a related group of Dumble place-names. Within this jumb-root area, occurrences of jump-root place-names are also considered. Jumbo's semantic relationship to jumble and the concept of discorder is discussed within a diachronic framework that includes both English and Scots. Metaphorical links to 'landscape as container' are noted. PIE and continental etyma are discussed in the context of the Norse settlement of northern England, which is s een as the home of jumb as an expression of a riverine feature. It is argued that jumb is the Danelaw equivalent of West Saxon cumb and its variants, and the result of a process of West Germanic velar palatalisation.