Meaning of long twelve in English:

long twelve

Pronunciation /ˌlɒŋ ˈtwɛlv/

noun

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

    ‘Long twelves’ are between ‘short twelves’ and ‘short thirteens’ in size, and Holme (1688) suggests that they are roughly twelve inches longer than the shortest slates in use, though other explanations of the name are possible (for example, that they were used for roughly the twelfth course or set of courses from the ridge).

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

    In duodecimo (12mo) schemes, in which each leaf is one-twelfth of a whole sheet, the more common arrangement was three rows of four shorter and broader pages.

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

Origin

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