Anglicized spelling of Síle, the Irish Gaelic form of Cecily. This name has become so common and widespread that it is hardly felt to be Irish any longer. In Australia since the 19th century it has been a slang generic term for any woman.
English: possibly a habitational name from Clayhidon in Devon (recorded as Hidon, Hydon up to the end of the 15th century), which was originally named from Old English hīeg ‘hay’ + dūn ‘hill’, or from any of the places named Iden (see Iden), of which there are two examples in Kent and one in East Sussex. In medieval records these all occur with the spelling Hiden or Hyden.