friend: is generally someone with whom I've mutually agreed to not be hostile. Closer to me than an acquaintance, but the term doesn't carry any connotation of openness or safety or support. If someone says "let's just be friends", I hear "we'll agree to not be enemies in the future, but not necessarily anything more."

That's sad, to me. Friend does not mean simply "we have agreed not to be hostile." Friend, to me, means "someone who gives a damn if something happens to you."