Sextant, a sixth part of certain things. The Romans having divided their as into twelve 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 cyathi.

Astronomy, a constellation of the southern hemisphere, made by Hevelius out of unformed stars. In Hevelius's catalogue it contains eleven, but in the British forty-one stars.