Is it farther or further?
1640s, from Latin vitreus "of glass, glassy," from vitreum "glass," which perhaps was so called for its color (cf. vitrium "woad"). Vitreous humor attested from 1660s.
vitreous vit·re·ous (vĭt'rē-əs)
Of, relating to, resembling, or having the nature of glass; glassy.
Of or relating to the vitreous body.