Though cultural understandings of what it means to be a woman or a man have gone through times of reconsideration and debate, it is arguably the case that at no other point in recent history have the definitions of “woman” and “man,” “male” and “female,” “masculine” and “feminine,” been more up for grabs than the present. To resolve these definitional controversies, we need to consider carefully the political, practical, and ethical dimensions of the act of defining.