What is portmanteau in linguistics?

In linguistics, a portmanteau refers to a word that combines the sounds and meanings of two or more words, creating a new word with a blended meaning. An example is “brunch,” combining “breakfast” and “lunch.” For example: smog = smoke + fog, hangry = hungry + angry, brunch = breakfast + lunch, motel = motorway + hotel, spork = spoon + fork, podcast = ipod + brordcast, workholic = work + alcoholic. infomercial + information + commercial, and edutanment = education + entertainment, etc.