using "HIS/HER cellphone" ?

People sometimes say things like this when the gender is unknown. But this is one of those cases where it actually sounds a bit strange to me.

I think that, if I didn't know the gender in this case, I would just say "a cell phone".

I know they do, however, I suggest this should be tagged as "popular" english or something, because it is grammatically incorrect.

Nope. People have been doing this for centuries. English is a language that is defined by what people speak. There is no "authority" like with French and some other languages. So if everyone says it, it is correct.

The only reason this is considered "incorrect" (and certainly not grammatically, as it could refer to a different "they" in context) is because some prescriptivists decided they didn't like it...

>English is a language that is defined by what people speak.

Yes it is very much and I'll remind you so in due time...

In this sentence "his or her" would sound stange to me. Because of the problems of gender in the English language the use of "their" when the gender is unknown is common, though, as Sacredceltic points out, grammatically incorrect. I'll put a "non-standard grammar" tag on this one.

thank you...

> grammatically incorrect.

[citation needed]

Most style guides I have seen take an officially neutral position on this debate. And English is based on consensus, not voting or authority.

Also, as I tried to say before, this is definitely not grammatically incorrect. However, it *can* be semantically incorrect, if you start with the assumptions that "their" refers to the bystander, and that "they" can't be singular.