Fourth and Fifth Declension Nouns

The most frequently used feminine nouns in the fourth declension are domus “house” and manus “hand”. Many other fourth declension feminine nouns are the names of trees. manus declines like portus, but domus is irregular in that it sometimes employs case-endings from the second declension; see Chapter 15, for the locative domi and the ablative domo.

Some ancient grammarians claimed that the neuter nouns of the 4th declension were indeclinable throughout the singular, but there is good evidence for -us in the genitive and indeed for -ui as an alternative form in the dative.

genu and “knee” are cognate (as are cornu and “horn”), being derived from the same word in IndoEuropean; the k in “knee” was still pronounced in Old and Middle English.

The fifth declension is a very small group, so little used that dies and res are, in fact, the only such nouns for which we have evidence for all the forms. Cicero specifically says that he would be reluctant to use the forms specierum and speciebus.

These forms come under scrutiny by Nosoponus in Erasmus’ Dialogus Ciceronianus; see the Fetutinae to the Introduction. specierum occurs 3 times in Apuleius and twice in the Digest, but speciebus is unremarkably frequent. Cicero might have done better to object to speciei, which occurs only twice in the grammarians [both gen., not dat., sing.].

The other Italic languages make less use of the fifth declension than does Latin, and no other IndoEuropean languages have a comparable declension. The majority of fifth declension nouns have a nom. sing. ending in -ies, and almost all nouns with an ending in -ies in the nom. sing. are fifth declension and feminine. Exceptions are abies, abietis fem. 3 “fir tree”, aries, arietis masc. 3 “ram”, paries, parietis masc. 3 “wall”, (re)quies, (re)quietis fem. 3 “rest”. (requies, however, favors the fifth declension form of the accusative, requiem, and requie is occasionally found as the ablative.)

When dies is feminine, it usually refers to a specific day, but usage seems to vary from one author to another. Heterogeneous nouns are fairly numerous, but many are rarely used, or one gender predominates strongly. Perhaps the other most widely used of such nouns are finis, -is 3, “end”, usually masculine, but sometimes feminine (in Italian, fine is feminine when the sense is “conclusion”, but masculine when the sense is “purpose”), and locus, -i 2, “place”, which seems to be always masculine in the singular, but usually neuter in the plural, masculine only when it refers specifically to passages in a book or topics for discussion. loca will originally have been a feminine singular collective noun (“places” = “region”). Such a shift from the feminine singular to the neuter plural occurs very extensively in Sanskrit and Greek, and explains why, in those languages, neuter plural nouns, when used as the subject, take a singular verb.