noun1. a title, heading, direction, or the like, in a manuscript, book, statute, etc., written or printed in red or otherwise distinguished from the rest of the text.
2.a direction for the conduct of divine service or the administration of the sacraments, inserted in liturgical books.
3. any established mode of conduct or procedure; protocol.
4. an explanatory comment.
5. a class or category.
adjective1.written, inscribed in, or marked with or as with red; rubrical.
2. red; ruddy.