the form of a circle; circumscribed by a circle; spherical, &c. &c. It is also applied to a letter or paper, of which a copy is sent to several persons on some common business.

Circular Instruments, a general name for those astronomical and nautical instruments used for measuring angles, in which the graduation extends round the whole circumference, or to 360°.

Circular Numbers are those whose powers terminate in the roots themselves; as 5 and 6, whose squares are 25 and 36.

Circular Sailing is the method of sailing by the arc of a great circle. See Navigation.