The spellingbee word was "prognathous", which is an adjective meanting the lower jaw extends further forward
than normal. But search yielded only "prognathism"= the
condition. There used to be a comic strip, "Andy Gump" who
had "retrognathism", meaning his lower jaw was shorter than
normal. Here's a URL about him:
http://www.toonopedia.com/thegumps.htm