Brewer's: Questa Gentilissima
(Italian). Most gentle one, a love term used by Dante to Beatrice
“Common mortals stand and gaze with bated breath while that most gentle one (questa gentilissima) goes on her way” —Mrs. Oliphant: Makers of Florence, p. 25.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894