The Allen and Greenough is still under construction;
so some links may not work quite the way you would expect.
100. Many of these nouns, however, are used in the
plural in some other sense.
a. The plural of a proper name may be
applied to two or more persons or places, or even things, and so become
strictly common: -
- duodecim Caesarés,
the twelve Caesars.
- Galliae, the two Gauls
(Cis- and Transalpine).
- Castores, Castor and
Pollux; Iovés, images
b. The plural of names of things reckoned
in mass may denote particular objects: as, aera, bronze utensils, nivés, snowflakes; or
different kinds of a thing: as, áerés, airs (good and bad).
c. The plural of abstract nouns denotes
occasions or instances of the quality, or the like: -
- quaedam excellentiae, some
cases of superiority; ótia,
periods of rest; calórés,
frígora, times of heat and cold.