Harry Potter Etymology | Patronus Charm (“Expecto Patronum”)
Patronus means “protector”, “guardian”, or simply “patron” in Latin, specifically reflecting the entire role that the Patronus Charm plays. In archaic Latin, it meant “father”, which is very interesting, considering that Harry Potter’s Patronus is the same as his father’s Patronus and Animagus form, a stag. The Latin word exspecto or expecto means “I look out for” or “I wait for”, thus the charm’s incantation roughly translates into “I await a protector.”
Emma Stone & Andrew Garfield | on the set ‘The Amazing Spider Man 2’ NYC [May 18,2013]