Asklemmy

I think it's context, really.

If you are given a clinical description of someone:

• blonde
• female
• good at math
• etc..

Then there's nothing negative about it. But if you use it in a way that implies or denotes value - objectifies, then it becomes offensive (i think..)

"What does this female want?" - implies that something about being female changes the speaker's attitude about the request

"You're such a female" - implies femaleness to have expected negative/positive traits that are being used as a blanket assumption for the subject.

"I chose Joey over the female" - implies that "the female" is less appealing than Joey by virtue of femaleness.

There is also something arbitrarily negative about using the clinical "female" over the less clinical "woman" or "girl" in these kinds of instances; although either has the potential be equally objectifying, especially if you consider the more abstract concept of "tone" and history of the speaker...

A lot of it is contextual nuance, and even then not everyone's feelings on it are the same. To be safe though, I would avoid referring to someone as female unless it's factually relevant.