Third (?), n. 1. The quotient of a unit divided by three; one of three equal parts into which anything is divided.
2. The sixtieth part of a second of time.
3. (Mus.) The third tone of the scale; the mediant.
4. pl.(Law) The third part of the estate of a deseased husband, which, by some local laws, the widow is entitled to enjoy during her life.
Major third(Mus.), an interval of two tones. — Minor third(Mus.), an interval of a tone and a half.