What do you consider a s l ut?

i don't think it's right to define someone that by the number of people they've slept with. i'm seventeen, i've had sex with 18 different guys. i don't get called a s l ut ever. and i have a lot of friends and a good life. but i know people who have had std's and only had sex with a few people and they get called names every day. i don't think that's right either. cause it could happen to anyone. i'm just lookin for opinions.. what would you consider a sl ut? i believe that it's girls that dress very revealing, openly are all over guys, and have no shame. basically bragging about their sex lives. like with me, not a single person knows how many people i have slept with, and i know every single guy and still talk to them and hang out with them. i don't have one night stands with strangers i just met, they're all guys that i've known for awhile and can continue being friends with.