fourth

Definition (noun): following the third position; number four in a countable series

Definition (noun): one of four equal parts

Example: a quarter of a pound

Definition (noun): the musical interval between one note and another four notes away from it

Definition (adjective): coming next after the third and just before the fifth in position or time or degree or magnitude

Example: the quaternary period of geologic time extends from the end of the tertiary period to the present

Definition (adverb): in the fourth place

Example: fourthly, you must pay the rent on the first of the month