The word locus is masculine in the singular, but it can be masculine or neuter in the plural. Geographical places are loca, but places in a text are loci. As far as I know, this is the only Latin word with such behaviour.

Do we know where this "double plural" comes from? Was it always there in the written Latin we know? Is there a similar situation in related languages (Italic, Greek, PIE, or something) that could shed some light on the problem?

  • 1
    De Vaan is silent on the plural, but LSJ does mention an inscription (Inscr. ap. Grut. 129, 14) which has a singular locum. I suppose it's possible that an old neuter existed that was lost. The inscription is probably a back-formation, though.
    – cmw
    Commented Dec 6, 2016 at 15:20

1 Answer 1


As usual, to answer this question we need to step into our comparative linguistics-fueled time machine and go back to Proto-Indo-European times, so we can see what function the ending -a, which we know as a neuter plural ending, had in PIE.

In PIE, this ending -a (or rather *-(e)h₂) did not form plurals, but collectives. A collective refers to a group of objects, but is conceptualized as being a single thing, and for grammatical purposes is generally treated as a singular noun; this was probably the case in PIE, and is why in Greek, for example, neuter plural nouns in -a still take singular verbs.

PIE collectives seem to have been used most often with neuter nouns -- in fact, neuter nouns don't seem to have had a normal plural (at least not in the nominative/accusative), so the collective form more or less stood in for a plural. This is why in Latin and other languages, -a came to be a specifically neuter ending.

But the collective could also be formed from masculine and feminine nouns. Locus is one such example: of its two plurals, locī continues the PIE plural, while loca continues the PIE collective. Lewis and Short describe the difference in meaning as follows: "plur. loci, single places; loca, places connected with each other, a region" -- where the plural vs. collective meanings are clear. Locus actually isn't the only such noun in Latin: there's iocus "joke", pl. ioca, and carbasus "sail", pl. carbasa. And there's at least one case in which the collective was reinterpreted as a feminine singular: pila "ball", which seems to have originally been the collective of pilus "hair" (meaning "mass or ball of hair").

(By the way, another heterogeneous noun with a similar story behind it is frēnum "rein", pl. frēnī. In this case the Latin masculine plural ending continues what was in PIE terms not a plural at all, but a neuter dual.)

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    One little question: Does the difference between the origins of loci and loca explain the difference in meanings in Latin? Or is it just coincidental that some meanings are plural and some collective?
    – Joonas Ilmavirta
    Commented Dec 6, 2016 at 18:51
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    @JoonasIlmavirta, there's probably more to it than this, but L&S describes the difference in meaning as follows: "plur. loci, single places; loca, places connected with each other, a region" -- where the plural vs. collective meanings are clear.
    – TKR
    Commented Dec 6, 2016 at 20:11
  • @TKR, does this mean that if I'm talking about places unconnected with each other ("He has friends in many places") the plural is loci? Commented Jan 3, 2017 at 13:00
  • @JoelDerfner, L&S seem to imply such a difference, but I don't know whether usage bears this out.
    – TKR
    Commented Jan 4, 2017 at 3:06

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