The Allen and Greenough is still under construction;
so some links may not work quite the way you would expect.
127. Compounds in -dicus (saying) and -volus (willing) take in their
comparison the forms of the corresponding participles dícéns and voléns, which were anciently used as
- maledicus, slanderous; maledícentior, maledícentissimus.
- malevolus, spiteful; malevolentior,
a. So, by analogy, compounds in -ficus: -
- mágnificus, grand; mágnificentior, mágnificentissimus.