thirtieth Meaning, Definition & Usage

  1. noun position 30 in a countable series of things
  2. adjective satellite coming next after the twenty-ninth in position
    30th.

WordNet

Thir"ti*eth adjective
Etymology
From Thirty: cf. AS. þritigo&edh;a.
Definitions
  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.
Thir"ti*eth noun
Definitions
  1. The quotient of a unit divided by thirty; one of thirty equal parts.

Webster 1913