A portmanteau word is coined by combining two or more words into one. “Brunch,” for example, is made up from “breakfast” and “lunch.” Portmanteau words seem to be getting more common; “cyborg,” “edutainment,” and, for that matter, “internet” are all well known and recent. But the practice of combining existing words into new ones has been around for centuries, just like the word “portmanteau” itself.
A portmanteau was originally a kind of suitcase; particularly one made to carry on horseback. The word was adopted from French in the 1500s. And by the way, “portmanteau” is itself a kind of portmanteau; it’s made up from “port” (to carry) and “manteau” (a cloak). But it wasn’t used to refer to words until 1871 when Humpty Dumpty explained to Alice (when she was in Wonderland) about the words in the poem “Jabberwocky.” “Slithy,” explained Humpty, “was made up of ‘slimy and lithe’ and mimsy means ‘miserable and flimsy.’” Mr. Dumpty went on the explain: “You see it’s like a portmanteau—there are two meanings packed up into one word.”
Technically, a portmanteau (when it’s a word) shouldn’t just take two words as-is and put them together. That’s a compound. (So really “portmanteau” doesn’t qualify as a portmanteau, but oh come on.) And it’s also not a contraction, because contractions are combinations of two words that are used in sequence, like can + not making “can’t.” Also contractions nearly always contain apostrophes to show where something has been left out. (But there are a few that don’t; I gotta list some sometime — or at least I oughta.)
You can have fun making your own portmanteaus, too. If you think you’re experiencing sore joints because you drive your car instead of walking, maybe what you have is “carthritis.” If you find “portmanteau” to be much to French for your taste, maybe “backpacronym” would be better. Or if you’re trying to explain about text messages dealing with etymological trivia, how about calling them “tidbitymological” or “textraneous?”
Those samples came from a portmanteau generator, which you can try here: https://www.punchlinedesign.net/pun_generator
