It's not a matter of opinion, it's a matter of definition. I know what basic words mean. People can only disagree with the statements I made by destroying the meanings of the words I used. It's no big surprise that they're trying to do that, considering the source of this stuff is postmodernism.

We can define "man" as someone's mental state.

Or we can define "man" as having XY chromosomes.

Before any debate can occur both parties need to agree on terminology and definitions.

Alternatively the argument could be about the legitimacy of the definitions themselves. Was liberty taken to redefine a word without standing?

That would depend on the definition being used for "man".

If the definition of "man" is someone's mental state, then yes there may have been billions of pregnant men throughout history.

Are you able to provide a source for that statement? All I could find were theoretical procedures that have not been performed.

A man cannot get pregnant. This is not something that any medical advance can change.