alexandrine
noun
al·ex·an·drine ˌa-lig-ˈzan-ˌdrēn 
-drən,
-ˌdrīn,
ˌe-
often capitalized
: a line of verse of 12 syllables consisting regularly of 6 iambs with a caesura after the third iamb
alexandrine adjective
Example Sentences
Recent Examples on the Web The score is Michel Legrand's finest, with various jazz elements, lyrics in alexandrines by Demy, and intricately structured reprises that match the poetic, crisscrossing plot. 
Patrick Friel, Chicago Reader, 16 Feb. 2018
Patrick Friel, Chicago Reader, 16 Feb. 2018 Word History
Etymology
French alexandrin, adjective, from Alexandre Alexander the Great; from its use in a poem on Alexander
First Known Use
1589, in the meaning defined above