The common noun ke/krwy had both of the senses given. That of "knave" (as an extension of the Kerkopes: kappa 1405, kappa 1406) is the usual sense in antiquity (LSJ s.v. I). The sense "ape" turns up in Byzantine Greek, based on the fact that the Kekropes were man-monkeys. LSJ s.v. II cites only an instance in the astrological corpus published by Manitius; but the sense is clear in John Lydus (6 CE), On Months 3.11: "and that is why the Egyptians have the custom of honouring the ibis and the kerkôps; for both animals are considered in concord with the Moon".
On Kekrops (the second vowel is omicron) see kappa 1272.
[1] Gloss taken from Photius and the Lexica Segueriana, and similarly elsewhere.