What is a "portmanteau"?
A portmanteau 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 should be distinguished 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.
Other Examples of a Portmanteau:
telephone + marathon = telethon
medical + care = Medicare
parachute + troops = paratroops
camera + recorder = camcorder
web + log = blog
breakfast + lunch = brunch
spoon + fork = spork
costume + play = cosplay