“Forecast” evolved from the same root as the “cast” we’re talking about here, but usage is everything. “Forecasted” has been established as a valid word due to usage, but still, I think “forecast” is used as the past tense a lot more often than “forecasted”, though it varies with the subject matter.
I myself prefer to stick with “forecast” as the past tense except in special cases. One special case would be where’s it’s turned into an adjective in a phrase like “forecasted demand”, where the inflection helps to resolve ambiguity, and resolving ambiguity should always be a virtuous principle in language.
In modern times “casted” is just not a word. That much is not debatable. (The medical usage noted earlier I’d just regard as a specialized colloquialism.) “Forecasted” is.
If you extend your search to quotations for other headwords, you’ll find that “casted” has indeed been used later than the sixteenth century, albeit only in compounds and other derived forms. Load has quotations referencing “load-casted current markings” and “load-casted ripples”, from 1957 and 1972, respectively. And of course there’s “forecasted”, which is listed as a past participle of forecast, with a quotation from 1882.
Actually, whether or not an expression is “correct” is pretty much determined by whether “lots of people” are saying it. Much of what you’re writing now would be cringe-inducing, or even complete gibberish, to English speakers of times past. You think “went” shouldn’t be the past participle of “go”, but once upon a time nobody thought it should be the simple past tense of “go” either. (“Went” was the past tense of a completely different verb, “wend”. But gradually people started using it as the past tense of “go”, until by the 16th century it was more or less standard.)
Not quite. People have to both say it and believe it is correct. An obvious example would be “ain’t,” which has been in use since the 18th century but is still not considered “correct.” It may be used for stylistic reasons, but it’s still not considered proper English.
“Have went” doesn’t even have that distinction. It has a long, long way to go before becoming “correct.”
Yip. I believe it refers to the meaning of casting something into a mold. Which is a bit odd, since no such mold is actually used. But it does use the classic molding material Plaster of Paris.
(I tried to find some citations to confirm the etymology of this particular definition, but I could not.)
Protip: libraries, even vanilla public libraries subscribe to a number of databases and often they include the online OED. If you have a library card, more likely than not, you can get into the OED through your local library’s online research portal.
Excepting production errors, I think it’s safe to say that if a person says it, they believe it to be correct.
And proper english is an arbitrary standard. The proper variety of english for a given situation is going to depend on who the listeners are, what relationship the speaker wishes to cultivate with the audience and the geographical location of the exchange.
In my variety of English (which is Hiberno-English), the past tense of forecast is “forecast”. As in “last week, I forecast that we would lose the game, and today we did.”
