(US) The Fourth of July.

(informal) To agree with a proposition or statement after it has already been thirded.

(in the singular) The person or thing in the fourth position. / (chiefly US) A quarter, one of four equal parts of a whole. / (in the singular) The fourth gear of an engine.

The ordinal form of the number four.

plural of fourth

The quality of being or coming fourth.

simple past tense and past participle of fourth

present participle of fourth

One of thirty-four equal parts of a whole.

(algebraic geometry) The fourth coordinate indicating a position along the fourth axis. / (physics) The dimension of time.