1) Last day of some months 2) Ordinal 3) Pearl anniversary 
• (n.) The quotient of a unit divided by thirty; one of thirty equal parts. • (a.) Next in order after the twenty-ninth; the tenth after the twentieth; -- the ordinal of thirty; as, the thirtieth day of the month. • (a.) Constituting or being one of thirty equal parts into which anything is divided.
Thir'ti·eth adjective [ From Thirty : confer Anglo-Saxon þrītigōða .] 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 o...
[adj] - coming next after the twenty-ninth in position 2. [n] - position 30 in a countable series of things
30th adjective coming next after the twenty-ninth in position