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1580s, "traveling case or bag for clothes and other necessaries," from Middle French portemanteau "traveling bag," originally "court official who carried a prince's mantle" (1540s), from porte, imperative of porter "to carry" (see porter (n.1)) + manteau "cloak" (see mantle (n.)).
Portmanteau word "word blending the sound of two different words" (1882), coined by "Lewis Carroll" (Charles L. Dodgson, 1832-1898) for the sort of words he invented for "Jabberwocky," on notion of "two meanings packed up into one word." As a noun in this sense from 1872.
a word composed of parts of two or more words, such as chortle from chuckle and snort and motel from motor and hotel. The term was first used by Lewis Carroll to describe many of the unusual words in his Through the Looking-Glass (1871), particularly in the poem "Jabberwocky." Other authors who have experimented with such words are James Joyce and Gerard Manley Hopkins.