1. The ordinal of four.

2. One of four equal parts of a whole; an interval composed of two tones and a semi-tone.

Nuttall's Standard dictionary of the English language By Nuttall, P.Austin

• ourth,
• forthe,
• bourth,
• fourthy,
• foruth,
• fouht,
• bouth,
• gurth,
• turth,
• aouth,
• forthy,
• fuorth,
• douth,
• fourh,
• wouth,
• fiurth,
• furth,
• touth,
• foguth,
• fourrth

• FORET,
• forth,
• forte,
• four,
• foard,
• ford,
• forti,
• fort,
• further,
• Forde,
• forehead,
• forrad,
• forty,
• Fought.

The adverb form of "fourth" is "fourthly".

The adjective form of "fourth" is "fourth".

The plural of the "fourth" can be the "fourths".

The singular of the "fourth" can be the "fourth".