plural of thirteenth

The ordinal form of the number thirteen.

The person or thing in the thirteenth position. / One of thirteen equal parts of a whole. / (music) The interval comprising an octave and a sixth. / (in dates) The thirteenth day of a month.

A particular date combination that occurs when the thirteenth day of a month falls on a Friday, and which is considered unlucky in some cultures.

plural of Friday the thirteenth

plural of thirteenth grade

plural of thirteenth grader

(US, education, rare) A pupil who is in thirteenth grade.

(US, education) The year in school that comes after twelfth grade in some schools in the US, and that came after twelfth grade before 1988 in Ontario, Canada.