Term of Art: Portmanteau

“portmanteau: A single form which realizes two or more successive grammatical units, Typically of a morph, called a ‘portmanteau morph,’ seen as realizing morphemes: e.g. in French au theatre ‘to the theater,’ au is a single morph ([o]) which simultaneously realizes a preposition (elsewhere a) and the definite article (elsewhere le).”

Excerpted from: Matthews, P.H., ed. The Oxford Concise Dictionary of Linguistics. New York: Oxford University Press, 2014.