E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Questa Cortesissima (Italian).
Most courteous one; a love term used by Dante to Beatrice.
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I set myself to think of that most courteous one (questa cortesissima), and thinking of her there fell upon me a sweet sleepMrs. Oliphant: Makers of Florence (Dantes description).