The terms “set lunch” or “set menu” - meaning a prix fixe menu or table d’hôte - refer to the fact that the menu and the price are “set,” not to the fact that there is a “set” of items. Just as you wouldn’t say that such-and-such an item is “part of the fixe,” don’t say it’s “part of the set.”
I don’t know how this misuse has crept into usage, although it may have been via non-English speakers.
I’m not really sure what use you’re speaking about.
The word set has many definitions in English (nouns and verbs) one of which is a group of items.
A set of things is a number of things that belong together or that are thought of as a group.
There must be one set of laws for the whole of the country.
I might need a spare set of clothes.
The computer repeats a set of calculations.
Only she and Mr Cohen had complete sets of keys to the shop.[l
The mattress and base are normally bought as a set.
…a chess set.
Obviously what you describe is another meaning of “set.” That’s exactly what I said. But that meaning is incorrect when used in the case of a “set meal.”
Yes. I guess I’m just having difficulties understanding an Example that reflects what you are talking about … maybe I’m misreading your post somehow.
This would be a similar example: “Fixed” can mean " attached or set in one place and doesn’t move" as well as “repaired” or “corrected.” A “fixed price” menu doesn’t mean a menu where the price has been corrected, even though that’s one meaning of “fixed.” It means a menu where the price is set and doesn’t change.
Where are you seeing this misuse?
