My opinion? You're taken when you and a partner officially say that you're both seeing each other, may not be going out, but should probably not be seeing other people as well. bah gotta go, can't finish what i was saying argh
Is this a real question? Usually when you commit to someone and that other person commits to you then you are not single. You can be single if you have friends with benefits, acquintances, one night stands, etc. but as long as you make the commitment of being with some1 physically & psycologically then you're "taken".