The Allen and Greenough is still under construction;
so some links may not work quite the way you would expect.
289. Neuter Adjectives are used substantively in the
following special senses: -
a. The neuter singular may denote
either a single object or an abstract quality: -
- raptó vívere, to live by plunder.
- in aridó, on dry
- honestum, an honorable
act, or virtue (as a quality).
- opus est mátúrátó, there is
need of haste. [Cf. impersonal passives, § 208. d.]
b. The neuter plural is used to signify
objects in general having the quality denoted, and hence may stand for the
abstract idea: -
- honesta, honoroble deeds
- praeterita, the past (lit., bygones).
- omnés fortia laudant,
all men praise bravery (brave things).
c. A neuter adjective may be used as an
appositive or predicate noun with a noun of different gender
(cf. § 287. a): -
- tríste lupus stabulís (Ecl. iii. 80), the
wolf [is] a grievous thing for the fold.
- varium et mútábile semper fémina (Aen. iv. 569), woman is
ever a changing and fickle thing.
- malum mihi vidétur esse mors (Tusc. i. 9),
death seems to me to be an evil.
d. A neuter adjective may be used as an
attributive or a predicate adjective with an infinitive or a Substantive
- istuc ipsum nón esse (Tusc. i. 12), that very ``not
- húmánum est errare, to err is human.
- aliud est erráre Caesarem nólle, aliud
nólle miserérí (Lig. 16), it is one thing
to be unwilling that Caesar should err, another to be unwilling that he