Alexandrine
The twelve-syllable line, king meter of classical French poetry, traditionally cut at the hemistich.
The alexandrine is the French twelve-syllable line — Racine's, Hugo's, Baudelaire's. In its classical form it splits into two six-syllable hemistichs separated by the caesura, which imposes a central breath.
Its prestige comes from its amplitude: twelve syllables give room for a complete thought, an oratorical period, a natural binary swing. The Romantics and then the Symbolists loosened it (three-beat trimeters, straddled caesuras) before free verse dethroned it — without ever erasing it: its occasional return inside a free poem still produces instant solemnity. Counting it requires mastering the mute e, diaeresis and synaeresis. (In English prosody, "alexandrine" names the iambic hexameter line.)
Example
"A needless alexandrine ends the song / That, like a wounded snake, drags its slow length along."