IMO, if they have a single meaning in common that is recognized as being very nearly the same, then it can hardly be said that it is a "new" use. Perhaps one might have an edge over another in a particular context, but implying that it's out and out wrong I don't understand.
First off I'm not
implying that it's wrong, I'm stating explicitly that it's wrong. Indeed I thought I was being painfully explicit, but let me be even more so:
The initial statement that I was referring to praised the use of the word
gay in its original, non-sexual sense.
Praised is a key word here. Using
temerity in the context of praise is wrong. If you were teaching English to an advanced class of langauge students in say, Germany, you would point this out to them. It is the wrong word.
Temerity is not a term of praise. It means foolish boldness. If your student were to go out into the world and use the word in an attempt to express praise they would be making an error.
Audacity on the other hand, is a more flexible word. You might use the word to mean foolish or arrogant boldness, but you are not restricted to that sense of it. It can also mean admirable boldness, successful boldness. For example, MacArthur's landing at Inchon during the Korean War took audacity; the failed Bay of Pigs invasion during the Kennedy administration would be more of an example of temerity.
As to having some meanings in common, the question is
which meanings? The original poster meant to express admiration, and it is this meaning which is NOT shared by the two words. Or, more importantly, the note of praise that the writer meant to convey is missing from temerity, which conveys just the opposite sentiment.
