1911 Encyclopædia Britannica/Pretty

PRETTY, a word usually applied in the sense of pleasing in appearance, without connoting those qualities which are described as beautiful or handsome. In Old English praettig meant tricky, cunning or wily, and is thus used to translate the Latin sagax, astutus, callidus, in a vocabulary of about 1000. Praett meant a trick, and this word is seen in many forms in Dutch, cf. the words prettig, sportive, part, trick. A connexion has been suggested with the Greek πρακτικός, πράττειν, to do, make, through Latin practica, practice, performance; but the New English Dictionary rejects these, as also Celtic sources, as unfounded. From “cunning” to skilful, and thence to its use as a term of general appreciation as is so often used by Pepys, the development is easy.