'alexandrine' originates from French, specifically the word 'alexandrin', where 'alexandrin' referred to a type of verse used in the 'Roman d'Alexandre'.

'alexandrin' transformed into the English word 'alexandrine' and has been used in English poetry since the 16th century.

Initially, it referred to a specific type of verse used in French literature, but over time it became a standard term for a 12-syllable line in English poetry.