American Dictionary of the English Language

SEX'TANT, noun [Latin sextans, a sixth. the Romans divided the as into 12 ounces; a sixth, or two ounces, was the sextans.]

1. In mathematics, the sixth part of a circle. Hence,

2. An instrument formed like a quadrant, excepting that its limb comprehends only 60 degrees, or the sixth part of a circle.

3. In astronomy, a constellation of the southern hemisphere which, according to the British catalogue, contains 41 stars.