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Latin Grammar I, Lesson 26. Nouns Irregular in Case

In the previous lessons, we introduced the study of irregular nouns in Latin and looked at nouns which are irregular in Number (23), Gender (24) and Declension (25). As said before, this is not intended to be an exhaustive study of irregular nouns because that would not be a good use of time. Our goal is to simply become aware of irregular nouns so that when you see them, you are not confused. In this lesson, we will study irregular nouns which are irregular with regard to case.

To complete the objectives of this lesson, complete the following tasks:

  1. Study the lesson for mastery.
  2. Complete the lesson assessment.

The content of this lesson is taken from chapter 26 of Alvarez’s Latin Grammar.


I. Quaedam non declinantur in casus, ut frugi, pondo, quod numerum pluralem tantum habet, cum libram significat; item quatuor, quinque et cetera cardinalia usque ad centum: quae aptota sive monoptate appellantur.

Translation: Certain (nouns) are not declined in a case, as frugi, pondo, which the plural number only have, when it signifies a weight; likewise, four, five, and the other cardinal numerals even to one hundred: which are called “aptotes” or “monoptotes”.

Nouns that deficient in their cases can be of several kinds. “Aptotes” are nouns that do not vary in case, but have one form for all uses. Some modern Grammar books refer to these as “indeclinable nouns”. A common example is the noun nihil (nothing), which has only one form. The fourth declension nouns cornu and genu, have the same forms through most or all cases–which is really to have no case forms. All nouns that are used to name numerals from three to one hundred are such.

The second class of nouns irregular in case are called “monoptotes”. These are nouns of one case only–and that not the nominative case. These are words that are used only in special expressions, such as noctu (by night), natu (by birth), iussu (by commandment), astu (by deceit), promptu (with speed)–all of which are ablatives.

II. Quaedam vocativo carent, cujusmodi sunt interrogativa, ut quis, qualis; relativa, ut qui, quae, quod; negativa ut nemo, nullus; partitiva pleraque, ut quidam, ullus, alius. Pronomina etiam, praeter tu, meus, noster, nostras, ferme vocandi casus destituuntur.

Translation: Certain nouns are lacking in the vocative case, of which kind are interrogatives, as quis (who?), qualis (of what kind?); relatives, as qui, quae, quod (who, which); negatives, as nemo (no one), nullus (none); most partitives, as quidam (a certain), ullus (any), alius (another). Pronouns also, besides tu (you), meus (my), noster (our), nostras (our own), commonly are deprived of the vocative case.

The vocative case is used when addressing a person or thing directly. It is easy to understand that if a noun is used to signify a person or thing that cannot be addressed directly, no vocative case form would exist.

III. Quaedam nominandi, interrogandi et accusandi casum habent, ut tantundem, tantidem.

Translation: Certain nouns have the nominative, genitive and accusative case, as tantundem (just so much), tantidem (of just so much).

IV. Quaedam nominativum et vocativum, as Jupiter, exspes.

Translation: Certain nouns have the nominative and vocative, as Jupiter, exspes (hopeless).

V. Quaedam obliquos tantum, ut Jovis, Jovi, Jovem, Jove.

Translation: Certain nouns only have the oblique cases, as Jovis (of Jupiter), Jovi (to Jupiter), Jovem (Jupiter), Jove (from Jupiter).

Note in rules IV and V above that the Latin nouns Jupiter and Jovis are treated as two separate irregular nouns. Modern books often present them together as an irregular declension of one noun.

VI. Quaedam tres solum obliquos, ut opis, opem, ope.

Translation: Certain nouns have only three oblique cases, as opis (of help), opem (help), ope (from help).

VII. Quaedam duos, ut suppetiae, suppetias; repetundarum, ab his repetundis; fors, a forte.

Translation: Certain nouns have only two cases, as: suppetiae (aids), suppetias (aids), repetundarum (of bribery) ab his repetundis (from bribery), fors (chance) a forte (from chance).

VIII. Quaedam unum, ut inficias, sponte, natu: quanquam etiam spontis apud Columellam et Celsum legitur.

Translation: Certain nouns have one case, as inficias (denial), sponte (by free will), natu (by birth): though spontis is also read with Columella and Celsus.


As in the previous lesson, this lesson simply introduces us to irregular nouns that are irregular in cases.

If you’d like to dig deeper into irregular nouns, study the chapter on Heteroclite nouns in Lily’s Latin Grammar.

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