"Rickert was the first woman (and second individual) to be awarded a Ph.D. in English letters and philology with that academic honor at the University of Chicago."
3.NounThe liberal arts, humanities, learning (broad accumulated cultural knowledge).
"Though architecture in ancient Rome was not generally considered to belong to the artes liberales, Vitruvius easily qualified as a man of letters because of his wide learning."
4.Verbthird-person singular simple present indicative of letter