"Terribilis" means terrifying, terrible. "This is a horrible
place." See also: en arcadia ego, Poussin, and
Rennes-le-Château.
*Update* Actually, the Latin phrase "Terribilis est locus iste"
is a biblical text commonly employed as a cantus firmus throughout
many Renaissance texts. From Gen 28:17, it translates to "Awesome
is this place." You'll see it in motifs dealing with the dedication
of cathedrals, as in Dufay's 1436 "Nuper Rosarum Flores" composed
for the consecration of Brunelleschi's dome in Florence.