I think I'm the start of the whole "socks are underwear" debate, so I'll weigh in. If I say "I have on new underwear" (can't imagine why I'd be saying that, but you get my drift) I mean my panties. However I consider socks, bras, panties, slips, etc. all to be part of the underwear 'category'. I consider pants, shirts, shoes to be outerwear - meaning they are the layer that is visible when fully clothed.