2) Nowadays, often a term for a friendship between a man and a woman which doesn't include a sexual element.
3) A friendship that lasts for as long as it takes for some twats to establish rumours about how the man wants to have off with the woman.
2. The process by which attractive and otherwise eligible women, when faced by proffered declarations of romantic interest by a male acquaintance, destroy the ego and spirit of said acquaintance by declaring that they only want to be "friends."
"I have feelings for you too, I don't want to do anything that could jeopardize our friendship. You're like a brother to me."