Tom7 is one of my favorite people, he is hilarious, has an amazing technical depth, and so much whimsy to go along with it. I'll proselytize for him all day!
This is actually a really interesting point. English portmanteaus usually work by combining all of one word with "half" (broadly construed) of the second word. Nopert fits the pattern precisely, including all of nope and half of Rupert.
The reason I find this so interesting is that Mandarin Chinese portmanteaus take a different standard form: instead of combining all of one word with half of the other word, they combine half of one word with half of the other word.
Think about how much you'd need to know about the structure of an arbitrary language before you'd feel confident predicting how it creates portmanteaus.
guesstimate, bromance, and tragicomic include all of each of their source words.
And just by looking at your list, you can see why the norm is to include all of one word - those are difficult to interpret for English speakers. Brunch, spork, and sitcom are well understood, though sitcom is more likely to be seen as an abbreviation than a combination. Probably cronut will be understood too, if someone's looking at one. Motel is obviously related to hotel, plus an inexplicable m. Smog is guessable. Cyborg and Velcro are completely opaque; those are just "words".
You're right, I shouldn't have said "rarely" -- thanks for helping me learn! You, also, shouldn't have said the first word is "usually" included. With help from an LLM and python looking at the 86 common portmanteaus, I found that the numbers are:
count percent
both 5 6.4
first word only 29 24.4 (you said "usually," I said "rarely")
neither 39 50.0
second word only 25 19.2
By the way, I called the code "portmantotal.py" :-)
Cyborg was not opaque to me, because I grew up reading science fiction so was very familiar with the concept of the cybernetic organism. My parents explained the origin of "velcro" to me when I was a kid and thought it was cool that it had two sides.
EDIT: While playing with the data in python, I realized that chatgpt included 8 duplicates in the above list originally. I will fix that and recalculate the numbers.
Also, I was thinking about compound words, like seatbelt, schoolbus, butterfly and marshmallow, where all of both words is included -- I don't consider those portmanteaus. And yet, the "both" category in my list is interesting: "covidiot" works because the words overlap, and "blogosphere" adds an extra letter. "Manspread," in my opinion, is also a portmanteau but it's hard to explain why I wouldn't just call it a "compound word" . Probably either because it's derived from "mansplain" or because it adds a noun to a verb whereas compound words are usually noun + noun.
I didn't realize the term applied to stuff like `sitcom`, I thought it was a requirement that the result used part of the start of one word and the end of another. TIL!
Motel and sitcom are portmanteaus -- they're some of the most common examples used when defining the term "portmanteau" .
"Blend" and "shortening" are necessary-but-not-sufficient synonyms for portmanteau. Your error here is that you imply "because it's a blend, it's not a portmanteau." All portmanteaus are blends. All portmanteaus are shortenings. Some blends are portmanteaus. Some shortenings are portmanteaus.
The coiner gets to pick the combination that sounds the best, there is no correct choice. We could have gotten breakfunch and mototel, but some person or collection of people decided that brunch and motel work better.
A good sense of humor to go with the math.