1. One of thirty equal parts.

2. The ordinal of thirty.

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

• thirtienth,
• thirtenth,
• thirtie,
• thirtith,
• thirtyth,
• thirtyith,
• thirteeth,
• thirthenth,
• rhirtieth,
• fhirtieth,
• ghirtieth,
• yhirtieth,
• 6hirtieth,
• 5hirtieth,
• tgirtieth,
• tbirtieth,
• tnirtieth,
• tjirtieth,
• thirtieeth,
• thirtyeth

• thirty-three,
• thwarted,
• thoriated,
• thirty-two,
• thirty-third.

The adjective form of the word "thirtieth" is "thirtieth".

The plural form of the word "thirtieth" is "thirtieths"

The singular form of the word "thirtieth" is "thirty-first"