Sextant, a sixth part of certain things. The Romans having divided their as into 12 ounces or uncia, the sixth part of that, or two ounces, was the sextans—Sextans was also a measure which contained two ounces of liquor, or two cyathei.

in Astronomy, a constellation of the southern hemisphere, made by Helvelius out of unformed stars. In Helvelius's catalogue it contains 11, but in the Britannic catalogue 41 stars.