THIRD, a. thurd. [L. tertius.] The first after the second; the ordinal of three. The third hour in the day among the ancients, was nine o'clock in the morning.

Third estate, in the British nation, is the commons; or in the legislature, the house of commons.

Third order, among the Catholics,is a sort of religious order that observes the same rule and the same manner of life in proportion as some other two orders previously instituted; as the third order of Franciscans, instituted by St. Francis in 1221.

Third point or tierce point, in architecture,the point of section in the vertex of an equilateral triangle.

Third rate, in navies. A third rate ship carries from 64 to 80 guns.

Third sound, in music. See the noun Third.

THIRD, n. thurd. The third part of any thing. A man takes land and tills it for one third of the produce; the owner taking two thirds.

1. The sixtieth part of a second of time.

2. In music, an interval containing three diatonic sounds; the major composed to two tones, called by the Greeks ditone, and the minor called hemiditone, consisting of a tone and a half.