- The eighth part of a circle; an arc of 45 degrees. - The position or aspect of a heavenly body, as the moon or a
planet, when half way between conjunction, or opposition, and
quadrature, or distant from another body 45 degrees. - An instrument for measuring angles (generally called a
quadrant), having an arc which measures up to 9O¡, but being itself the
eighth part of a circle. Cf. Sextant. - One of the eight parts into which a space is divided by
three coordinate planes.