(music) A musical interval of the Western twelve-semitone system consisting of four semitones and spanning three degrees of the diatonic scale. Major scales are so named because of the major third interval between the tonic and mediant of a major tonic triad. It is enharmonically equivalent to a diminished fourth.

A musical interval with exactly three half steps that spans two degrees of diatonic scale.

Most inferior in quality or standing.

plural of minor third

plural of major third

plural of third rail

(UK, law, obsolete) A third part of the profits of fines and penalties imposed at the country court, which was among the perquisites enjoyed by the earl.

A relief aircrew member, often used on long-distance flights.

plural of third eye

(anthropology) A category (a gender), present in societies which recognize three or more genders, which is neither male nor female; in some societies, the category may contain individuals who are intersex or androgynous, while other societies may categorize transgender people into it. (Compare fourth gender.)