The ordinal form of the cardinal number three; Coming after the second.

The person or thing in the third position.
One of three equal parts of a whole.
The third gear of a gearbox.
An interval consisting of the first and third notes in a scale.
third base
A handicap of one stroke every third hole.
A third-class degree, awarded to the lowest achievers in an honours degree programme
One sixtieth of a second, i.e., the third in a series of fractional parts in a sexagesimal number system. Also formerly known as a tierce.

(informal) To agree with a proposition or statement after it has already been seconded.
To divide into three equal parts.