| Noun | 1. | fourth - following the third position; number four in a countable seriesrank - relative status; "his salary was determined by his rank and seniority" | |
| 2. | fourth - one of four equal parts; "a quarter of a pound" | |
| 3. | fourth - the musical interval between one note and another four notes away from it | |
| Adj. | 1. | fourth - coming next after the third and just before the fifth in position or time or degree or magnitude; "the quaternary period of geologic time extends from the end of the tertiary period to the present"ordinal - being or denoting a numerical order in a series; "ordinal numbers"; "held an ordinal rank of seventh" | |
| Adv. | 1. | fourth - in the fourth place; "fourthly, you must pay the rent on the first of the month" | |