Glassophobia showed up way back in 1901 in a short story called The Glass Dog, which appeared in L. Frank Baum’s book, American Fairy Tales:
” ‘Call off your dog,’ he shouted, in terror.
‘I can’t, sir,’ answered the butler. ‘My young lady has ordered the glass dog to bark whenever you call here. You’d better look out, sir,’ he added, ‘for if it bites you, you may have glassophobia!’ ”
In 2007 glassophobia showed up as the fear of public speaking in an Ezine Article by Joann Grant titled Glassophobia - When Fear is A Disability!
There are at least two other possible fear-related meanings for glassophobia. One would be a fear of heights triggered when standing on a glass floor (like on a deck at the CN tower in Toronto) and looking down. Way back in 1960 Gibson and Walk studied babies placed next to a visual cliff, and found they could perceive depth and recognize that cliff was to be avoided (see this video).
The other possible meaning is fear of bumping into a metaphorical glass ceiling that prevents women or minorities from being promoted at work.
The half full glass and CN Tower floor view both came from Wikimedia Commons.