Does separated = single?

I was chatting with a friend yesterday about a new guy in our circle, and she said: "Hey, you're single for the moment, you should jump him. I would!"

She said it in passing, and we were cracking jokes but the comment startled me. I certainly don't feel single, but then again, aside from my rings and a piece of paper, there's nothing in my life that actually resembles being part of a couple anymore. Nor does it seem likely my husband and I will be again.

So. Is it time to take off my engagement and wedding rings? I already stopped wearing the other two precious rings my husband gave me...one, a beautiful emerald I'd been wearing since college and the second, an antique he gave me for Christmas the year after we were married.

Should I think about dating? I know there's no exactly right or wrong answer, but I'm wondering: Can you be separated and single at the same time?