'heterosexuality' originates from a combination of the Greek prefix 'hetero-' meaning 'other, different' and the Latin word 'sexualis' meaning 'relating to sex,' with the suffix '-ity' denoting a state or condition.

'heterosexuality' was formed in the late 19th century from 'heterosexual' (first used in the 1890s) plus the suffix '-ity,' and eventually became the modern English word 'heterosexuality.'

Initially, it meant 'the quality of being sexually attracted to the opposite sex,' and this meaning has remained consistent in modern usage.