Thirtieth — Defs

01 a. Next in order after the twenty-ninth; the tenth after the twentieth; -- the ordinal of thirty; as, the thirtieth day of the month.

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.
Constituting or being one of thirty equal parts into which anything is divided.

02 n. The quotient of a unit divided by thirty; one of thirty equal parts.