It’s not something that I have encountered in the UK at all but I feel like I might have heard it as a dialectical variant somewhere online, maybe in some engineering community of some region or other, but couldn’t say where.
It’s always amusing when people disparage words not found in their own dialect. The word “heighth” is the least changed descendant of the Old English word “hiehþu”, while the more common form “height” is the variant descendant.
nm. misunderstood.
“Heighth”: but the “gh” and the last “h” are silent.
Commonweal or Commonwealth?
For those speakers who merge “t” and “th” sounds as a dental stop (typical of working class accents in Ireland, Caribbean English, West African English), the question is moot.
I’m not sure what you mean about dialectical variations not becoming words. They don’t need to become words. They already are words.
I think what is meant is they aren’t separate words. They are a different way of pronouncing the same word. And they rarely become a separate word.
Out here in Hicksville, Kansas a lot of folks pronounce it with the ‘th’ at the end. Drives me bonkers, and I used to correct a lot of people when I hear it. Didn’t help, as my wife and her family mispronounce the word continually.
I don’t agree that heighth is not a separate word. There wouldn’t be instances of people saying it differently in different contexts otherwise. No, when people are saying words like width, depth, length, they think of a word that ends in -th.
Saying it’s not a word is like saying mischeivious or anyways aren’t words. People saying the first think there is an extra I, and people saying the second are not anyway with a weird S-sound at the end.
Yeah, it’s not a formal word. No, I don’t think it is likely to become one. But I do consider it a different word. I do not in fact pronounce “height” with a “th,” but I do occasionally forget the word “height” and say “heighth.”
I hope that makes sense.
I wouldn’t expect it to be a completely separate word, since it means the same thing.
But that doesn’t mean it’s ‘not a word’
You’ve got to fightth for the rightth to say heightth.
^^^ Same here.
They do sometimes become words used in other dialects. On occasion, a word used just in one dialect slowly gets picked up by users in other dialects. The speakers of those other dialects for some random reason find that it’s useful to use a word used in another dialect. If the speakers of the various dialects communicate with each other frequently, you can expect a word to occasionally move from one dialect to another one.
Well “heighth” isn’t a real word and I’ve never heard anyone use it. Height rhymes with kite.
I’ve heard people use it. I was able to figure out what they meant. I don’t use it usually, but it’s possible that I have used it a few times when I’ve been listening to other people say it.
The 56 member-states of the Commonwealth were part of the British Empire; now their voluntary association is meant to increase economic cooperation and other good things.
I haven’t heard of Commonweal Nations. (Which doesn’t prove anything either way.)
Good information on some of the English-speaking members in this post:

For those speakers who merge “t” and “th” sounds as a dental stop (typical of working class accents in Ireland, Caribbean English, West African English), the question is moot.
I get a little chuckle every time I re-watch Moonstruck, the first of two scenes when the John Mahoney character gets a drink thrown in his face. His date says “Kiss my aspirations” and Mahoney, a college professor, says “Kiss my aspirations. Very clever, the heighth of cleverness.” I’ve always taken the pronunciation as a bit of an insult to his character: although he’s a college prof he’s not all that bright. Here’s the scene:

It’s always amusing when people disparage words not found in their own dialect. The word “heighth” is the least changed descendant of the Old English word “hiehþu”, while the more common form “height” is the variant descendant.
I reminder looking this up when I first worked with a couple folks who pronounced it with a dental fricative. While it rhymes with kite for me, their pronunciation has plenty of historical precedence, and labeling it wrong or a mispronunciation is just indicative of the public’s general ignorance of how language works.
People without training in linguistics often misunderstand this. The fact that some groups of people use a dialect that is uneducated or lower-class or whatever doesn’t mean that what they are speaking (or writing, if they also use it in writing) isn’t language. Anything spoken by a group of people who understand each other is a variety of language. The fact that what they say displays their lack of education or poverty or race or ethnic ancestry or neighborhood doesn’t indicate that they aren’t speaking a language. Yes, it’s often necessary for them to learn the dialect of a group with more social esteem if they want to fit into that social class. But often that means that they must speak two dialects, one with the people they grew up with and one with the wealthier people. This is called code-switching. If anything, it could mean that they are smarter than those who only speak one dialect.