I can’t actually remember where I saw this, but I wrote it on my whiteboard some time ago as a potential WotW (as no one’s calling it), and who am I to disagree with the whiteboard?
So, prognathous is an adjective which describes someone or something with a protruding lower jaw or chin. You don’t see it so much in us homo sapiens these days, but it was common among Paleolithic humans. The etymology’s pretty straightforward – it comes from the Greek ‘pro’ for ‘forward’ and ‘gnáthos’ for jaw. ‘Normal’ people (by which I mean straight-jawed ones) are orthognathic, and people with overbites (i.e. me when I was at school) are retrognathic (or ‘goofy’ according to a particularly mean girl at St Mary’s Convent School).
Hmmm, this isn’t terribly interesting is it (it’s certainly no ‘avocado’)? I’m rather disappointed in my whiteboard.