A portmanteau (pɔːrtˈmæntoʊ/, /ˌpɔːrtmænˈtoʊ/; plural portmanteaus or portmanteaux /-ˈtoʊz/) or portmanteau word is a linguistic blend of words, in which parts of multiple words, or their phones (sounds), and their meanings are combined into a new word. A portmanteau word fuses both the sounds and the meanings of its components, as in smog, coined by blending smoke and fog, or motel, from motor and hotel. In linguistics, a portmanteau is defined as a single morph that represents two or more morphemes.
The definition overlaps with the grammatical term contraction, but contractions are formed from words that would otherwise appear together in sequence, such as do and not to make don't, whereas a portmanteau word is formed by combining two or more existing words that all relate to a singular concept which the portmanteau describes. A portmanteau also differs from a compound, which does not involve the truncation of parts of the stems of the blended words. For instance, starfish is a compound, not a portmanteau, of star and fish; whereas a hypothetical portmanteau of star and fish might be stish.