Latin adjectives can belong to the 1st and the 2nd declension (adjectives in -us, most adjectives in -er) or the 3rd declension (adjectives with other endings). Following words are declined like adjectives: - possessive determiners : meus, tuus, suus, noster, voster (the 1st and the 2nd declension) - demonstrative pronouns (with modifications - see the link) - and some other pronominal adjectives : ullus, nullus, uter, neuter, solus, unus, totus, alter, alius.


Adjectives in -us, -a, -um
They are declined according to the 2nd declension in masculine and neuter gender, and to the 1st declension in feminine. Examples : magnus, bonus, possessive words : meus, tuus, suus: magnus, magna, magnum : singular

case	masculinum	femininum	neutrum
nom.	magnus	magna	magnum
voc.	magne	magna	magnum
acc.	magnum	magnam	magnum
gen.	magni	magnae	magni
dat.	magno	magnae	magno
abl.	magno	magna	magno

Plural:

case	masculinum	femininum	neutrum
nom. voc.	magni	magnae	magna
acc.	magnos	magnas	magna
gen.	magnorum	magnarum	magnorum
dat. abl.	magnis	magnis	magnis

The word "meus" (my) has a unique vocative "mi" : mi fili - my son.

Adjectives in -er, -(e)ra, -(e)rum
They are declined according to the 2nd declension in masculine and neuter gender, and to the 1st declension in feminine. Examples : sacer, dexter, miser, possessive words : noster, vester. Some of them lose -e- before all endings, some of them maintain it : sacer, sacra, sacrum, noster, nostra, nostrum, but : miser, misera, miserum, alter, altera, alterum:
sacer, sacra, sacrum : singular

case	masculinum	femininum	neutrum
nom. voc.	sacer	sacra	sacrum
acc.	sacrum	sacram	sacrum
gen.	sacri	sacrae	sacri
dat.	sacro	sacrae	sacro
abl.	sacro	sacra	sacro

Plural:

case	masculinum	femininum	neutrum
nom. voc.	sacri	sacrae	sacra
acc.	sacros	sacras	sacra
gen.	sacrorum	sacrarum	sacrorum
dat. abl.	sacris	sacris	sacris

Peculiarities of pronominal adjectives
Pronominal adjectives ullus, nullus, uter, neuter, solus, unus, totus, alter, alius have irregular genitive singular in -ius and dat. sing. in -i in all genders :
gen. sg. : ullius, nullius, utrius, neutrius, solius, unius, totius, alterius, alius / alterius.
dat. sg. : ulli, nulli, utri, neutri, soli, uni, toti, alteri, alii.
Alius has two more specific forms : nom. acc. voc. neutri "aliud", its genitive alius is also often replaced with alterius.

Adjectives with other endings (3rd declension)
Adjectives with other endings (like omnis) are declined differently, according to the 3rd declension. The adjectives of 3rd declension have different forms in nom.voc.sing. (and acc.sg. neutri) and all other cases. They often change the form in gen. sing. Their gen. sing. has the ending -is.
Other forms can be formed on the basis of the genitive : -is changes to -i in dat. and abl. sg., -em in acc.sg. masc. fem., -es in nom. acc. voc. plur. masc.fem., -ia in nom. acc.voc. plur. neutri, -ium in gen.plur., -ibus in dat.abl.plur.

omnis, omnis, omne

case	masc. fem. sg.	neutrum sg.	masc.fem.pl.	neutrum pl.
nom. voc.	omnis	omne	omnes	omnia
acc.	omnem	omne	omnes	omnia
gen.	omnis		omnium
dat.abl.	omni		omnibus

Nom. sg. of 3rd declension adjectives can have two forms (omnis, omne), one form only - especially adjectives in -ens (ingens) or 3 forms (relatively rare situation).

ingens

case	masc. fem. sg.	neutrum sg.	masc.fem.pl.	neutrum pl.
nom. voc.	ingens	ingens	ingentes	ingentia
acc.	ingentem	ingens	ingentes	ingentia
gen.	ingentis		ingentium
dat.abl.	ingenti		ingentibus

The adjectives in comparative have two forms in nom. sing. -or and -us (superior, superius). They have abl. sing. in -e (superiore), nom. plur. neutri in -a (not -ia : superiora) and gen. plur. in -um (superiorum).

superior, superius

case	masc. fem. sg.	neutrum sg.	masc.fem.pl.	neutrum pl.
nom. voc.	superior	superius	superiores	superiora
acc.	superiorem	superius	superiores	superiora
gen.	superioris		superiorum
dat.	superiori		superioribus
abl.	superiore		superioribus