(Originally posted in Linguistics but I was told here is more appropriate)
When talking about a door, for example, we usually say:
"the door is open" and "the door is closed"
why don't we say:
"the door is opened" and "the door is closed" ?
Learn English – Why do we use open and closed instead of opened and closed
phrase-usage
Best Answer
The principal answer to almost all "why" questions about language is "because that's the way it is".
Sometimes, though, you can find a historical explanation of how things came to be - which does not answer the question "why", but can give some understanding.
In this case, the historical reason seems to be that the verb open comes from the adjective open (probably not in English, but in a prior state of the language). So open has had the adjectival meaning longer than it has been used as a verb.
In the case of close, though it seems to come ultimately from a Latin adjective (past participle clausum), within English (and the French we got it from) it was primarily a verb, and so the derived closed came into use. There is another reason as well: There is an adjective close in English - from the same root - and it has retained a few special uses with the meaning closed, as in close season; but in general it has taken the different meaning (and pronunciation) close = "near"), and the meaning shut is no longer available for the word.