Girl [Noun.]

‘[Middle English] In early use, this word referred to a child or young person of either sex. It is perhaps related to Low German gör ‘child’. In the late 18th century gal started to be used occasionally, representing a particular pronunciation. The phrase the girl next door to describe an ordinary and likable young women arose in film contexts in the 1950s.’

– Chantrell. G. edt. 2002. The Oxford Essential Dictionary of World Histories New York, United States: Berkley Publishing Group (2003) p. 232