According to my research just now (I do not pretend to have known all of these big words beforehand, but OP's question was so interesting that I did some googling), the linguistic term for this type of morphology (which means "the patterns of word formation in a particular language, including inflection, derivation, and composition") is full word suffix: "word types...formed on newly minted suffix-like formatives which are actually freely occurring full words". Formative in this grammatical context means "a derivational affix, particularly one that determines the part of speech of the derived word." (Source: Morphologie / Morphology. 1. Halbband edited by Geert E. Booij, Christian Lehmann, Joachim Mugdan, p. 968)
As other responders have pointed out (without using such high-falutin' linguistic terminology), the suffix -gate has, since the Richard Nixon/Watergate scandal of the early 1970s, come to mean "official scandal" and there are an uncountable number of instances of such derivations: Travelgate, Monicagate, Filegate, etc.