prop·to·sis \präpˈtōsə̇s\noun (pluralpropto·ses \-ōˌsēz\) Etymology: New Latin, from Late Latin, prolapse, falling forward, from Greek proptōsis, from propiptein to fall forward, from pro- pro- (I) + piptein to fall — more at feather : forward projection or displacement especially of the eyeball : exophthalmos