1. A title, heading, or initial section of text in a manuscript, book, or legal text, usually printed in red ink or in some similar distinguishing manner.
2. Any established rule of conduct or procedure.
3. A class or category.
4. An explanation of an obscure word in a text.
5. (Ecclesiastical) A direction in a missal, hymnal, or other liturgical book.
6. (Academic) A scoring guide used to evaluate the quality of students' responses.
1. Red or reddish.
2. Written in red.
Etymology: from Latin rubrica, red ochre, a type of red earth used for coloring.
If you do a Google image search on 'rubric examples', almost all of the results are for the academic definition.