THIRTIETH
Source: 567
Thir″ti‐eth (?), a. [[From Thirty: cf. AS. þrītigōða.]] 1. 1. Next in order after the twenty-ninth; the tenth after the twentieth; — the ordinal of thirty; as, the thirtieth day of the month.
2. 2. Constituting or being one of thirty equal parts into which anything is divided.