| a. | 1. | Next in order after the twelfth; the third after the tenth; - the ordinal of thirteen; |
| 2. | Constituting or being one of thirteen equal parts into which anything is divided. | |
| n. | 1. | The quotient of a unit divided by thirteen; one of thirteen equal parts into which anything is divided. |
| 2. | The next in order after the twelfth. | |
| 3. | (Mus.) The interval comprising an octave and a sixth. |
| Noun | 1. | thirteenth - position 13 in a countable series of things |
| Adj. | 1. | thirteenth - coming next after the twelfth in position Synonyms: 13th |