is said to be derived from Harlotta, the mother of William the Conqueror, but it is more likely to be a corruption of horlet (a little hireling), “hore” being the past participle of hyran (to hire). It was once applied to males as well as females. Hence Chaucer speaks of “a sturdy harlot ... that was her hostes man.” The word varlet is another form of it.
He was gentil harlot, and a kinde; A bettre felaw shulde man no wher finde
“The harlot king is quite beyond mine arm.”
Proverbial names for a harlot are Aholibah and Aholah (Ezek. xxiii. 4), probably symbolic characters; Petrowna (of Russia), and Messalina (of Rome).
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894