What is the X in X-mas?
12c., gosshien "make noises in the stomach," later (c.1400) "rush out suddenly, pour out," probably formed imitativeally in English under influence of Old Norse gusa "to gush, spurt," related to geyser. Metaphoric sense of "speak in an effusive manner" first recorded 1873. Related: Gushed; gushing. The noun is 1680s, from the verb.