Thirtieth

1. n. The quotient of a unit divided by thirty; one of thirty equal parts.
2. a. Next in order after the twenty-ninth; the tenth after the twentieth; — the ordinal of thirty; as, the thirtieth day of the month.
3. a. Constituting or being one of thirty equal parts into which anything is divided.

The word meanings were obtained from OPTED(The Online Plain Text English Dictionary), which is based on “The Project Gutenberg Etext of Webster’s Unabridged Dictionary” which is in turn based on the 1913 US Webster’s Unabridged Dictionary (See Project Gutenburg), as a text file.