ninetieth Meaning, Definition & Usage

  1. noun position 90 in a countable series of things
  2. adjective satellite the ordinal number of ninety in counting order
    90th.

WordNet

Nine"ti*eth adjective
Definitions
  1. Next in order after the eighty-ninth.
  2. Constituting or being one of ninety equal parts.
Nine"ti*eth noun
Definitions
  1. The quotient of a unit divided by ninety; one of ninety equal parts of anything.
  2. The next in order after the eighty-ninth.

Webster 1913