1. Determine the declension group to which an adjective belongs:

• if –a, -um, then 1^st/2^nd declension
• if not –a, -um, then 3^rd declension
• acer, acris, acre
• bellus, bella, bellum
• bonus, bona, bonum
• brevis, breve
• celer, celeris, celere
• dulcis, dulce
• felix (felicis)
• fortis, forte
• ingens (ingentis)
• iucundus, iucunda, iucundum
• liber, libera, liberum
• magnus, magna, magnum
• meus, mea, meum
• miser, misera, miserum
• multus, multa, multum
• noster, nostra, nostrum
• novus, nova, novum
• omnis, omne
• suus, sua, suum
• tuus, tua, tuum

• if 1^st/2^nd declension, drop –a or -um
• novus, nova, novum
• if 3^rd declension, drop neuter ending
• brevis, breve
• or drop (genitive) ending
• felix (felicis)

3: attach the appropriate endings depending upon the adjective’s declension group AND the case, number, and gender of the noun to be modified:

• -a, -um adjectives must take 1^st and 2^nd declension endings

• not –a, -um adjectives must take 3^rd declension i-stem endings

• An adjective takes the same case, number, and gender as the noun it modifies