What does "rogation" mean?

Rogation: (Eccl.) Litany; supplication. He perfecteth the rogations or litanies before in use. Hooker. Rogation days (Eccl.), the three days which immediately precede Ascension Day; -- so called as being days on which the people, walking in procession, sang litanies of special supplication. -- Rogation flower (Bot.), a European species of milkwort (Polygala vulgaris); -- so called from its former use for garlands in Rogation week. Dr. Prior. -- Rogation week, the second week before Whitsunday, in which the Rogation days occur.