Definition of long twelve in English:

long twelve

noun

  • 1A large roofing tile or slate, typically about 16 or 17 inches long (though perhaps varying regionally). Now historical.

  • 2Printing. An arrangement of pages of type in a form consisting of two rows of six long narrow-type pages.

  • 3A relatively long-barrelled gun for firing twelve-pound shells, formerly in naval use. Now historical.

Origin

Late 17th century; earliest use found in Randle Holme (1627–1700), herald painter. From long + twelve.

Pronunciation

long twelve

/ˌlɒŋ ˈtwɛlv/