The term is typically used in historical scholarship, and describes a very close relationship between people of the same sex during a period of history when "homosexuality" was not a social category as it is today. In this regard, the term was coined in the later 20th century in order to retrospectively describe a type of relationship which until the mid-19th century had been considered unremarkable but since the second half of the 19th century had become rarer as physical intimacy between non-sexual partners came to be regarded with anxiety. Romantic friendship between women in Europe and North America became especially prevalent in the late 18th and early 19th centuries, with the simultaneous emergence of female education and a new rhetoric of sexual difference.