The Allen and Greenough is still under construction;
so some links may not work quite the way you would expect.
128. Some adjectives are compared by means of the
adverbs magis, more, and
So especially adjectives in -us
preceded by e or i: -
- idóneus, fit; magis idóneus, maximé idóneus.
NOTE: But pius has
piissimus in the superlative, - a
form condemned by Cicer[QUERY] but common in inscriptions; equally common,
however, is the irregular pientissimus.