Adjectives as nouns

masculine = people in general,
feminine = women,
neuter = things.
meus propinquus [my neighour]
honestum [an honorable act, or virtue (as a quality)]
Omnes fortia laudant. [All men praise bravery (brave things).]
Varium et mutabile semper femina. [Woman is ever a changing and fickle thing.]
Malum mihi videtur esse mors. [Death seems to me to be an evil.]

Adjectives as nouns with added meaning from constant association
africus [ventus] [the southwest wind]
Ianuarius [mensis] [January]
vitulina [caro] [veal (calf's flesh)]
fera [bestia] [a wild beast]
patria [terra] [the fatherland]
Gallia [terra] [Gaul (the land of the Galli)]
hiberna [castra] [winter quarters]
triremis [navis] [a three-banked galley, trireme]
argentarius [faber] [a silversmith]
regia [domus] [the palace]