The Collaborative International Dictionary of English v.0.48:

Sextary \Sex"ta*ry\, n.; pl. Sextaries. [L. sextarius the
   sixth part of a measure, weight, etc., fr. sextus sixth, sex
   six.] (Rom. Antiq.)
   An ancient Roman liquid and dry measure, about equal to an
   English pint.
   [1913 Webster]