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: from the Germanic personal name Lanzo, originally a short form of various compound names with the first element land ‘land’, ‘territory’ (for example, Lambert), but later used as an independent name. It was introduced to England by the Normans, for whom it was a popular name among the ruling classes, perhaps partly because of association with Old French lance ‘lance’, ‘spear’ (see 2).