thirteenth

adjective

1. next after the twelfth; being the ordinal number for 13.
2. being one of 13 equal parts.

noun

3. a thirteenth part, especially of one (1/13).
4. the thirteenth member of a series.

adjective

1. (usually prenominal)
   1. coming after the twelfth in numbering or counting order, position, time, etc; being the ordinal number of thirteen: often written 13th
   2. (as noun)Friday the thirteenth

noun

2. 1. one of 13 equal or nearly equal parts of something
   2. (as modifier)a thirteenth part
3. the fraction equal to one divided by 13 (1/13)
4. music
   1. an interval of one octave plus a sixthSee also interval (def. 5)
   2. short for thirteenth chord

adj.early 14c., þriteenþe, from thirteen + -th (1), replacing forms from Old English þteoteoða. Cf. Old Norse þrettande, Danish trettende, Swedish trettonde, Old Frisian threttinde, Dutch dertiende, Old High German dritto-zehanto, German dreizehnte.