I am aware that I can hardly post what I'm about to post without inviting questions about how I found it. Well, my explanation, which you can choose to believe or not as you wish, is that I used the word 'decolletage' in something I'm writing, then realised I only vaguely knew what it meant; and so looked it up on Wikipedia, which redirected me here:
That's my story, at any rate, and I'm sticking to it. The page is a lot of fun on its own account, because Wikipedia is at its funniest when attempting to be po-faced about something it finds really, really exciting; but even better is the discussion page, in which various learned academics debate on how to improve the page. My favourite contribution is from this concerned scholar:
I am unable to find the terms used in this article to distinguish the various ways of exposing parts of the breasts ("cleavage décolleté," "cleavage centros," "cleavage côté," "cleavage underside," "cleavage cleavy") anywhere else on the Web except Wikipedia mirrors and bikini science. [...] I hope someone can cite authentic sources for these terms, or at least provide numerous photographs illustrating them from all angles.
I've no doubt you do, sir. No doubt at all.