The word fourth can mean:

• One of four parts of a whole
• An ordinal number following third
• Perfect fourth
• Augmented fourth or tritone
• The subdominant, and the chord built on the subdominant, is often simply called the fourth as it is the fourth scale degree.
• The Fourth of July, an American holiday

Other usages include:

• Fourth (Soft Machine album)

See also

• Forth (disambiguation)