look up any word, like bukkake:
1. a female who is sexually and emotionally attracted to other females but occasionally hooks up with males

2. a woman who considers herself to be a lesbian but hooks up with men on occasion

3. a lesbian who is sexually flexible
person 1: "I knocked on Ashley's door, but she wasn't home"
person 2: " Oh, yea she spent the night at Mark's"
person 1: "I thought Ashley was a lesbian"
person 2: "She is. Well kinda. She's a protean lesbian"
by sheezy402 December 19, 2011