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How to Form Latin Adjectives of the Third Declension

written by: John Garger • edited by: Rebecca Scudder • updated: 3/2/2012

Latin adjectives function similarly to those of English. However, their implementation in Latin is far more complicated since Latin is an inflected language. Learn how to decline Latin 3rd declension adjectives using Fortis, Potens, and Acer as examples.

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    Group One Latin adjectives consist of adjectives from both the first and second declension. These adjectives function identically to those of English. However, since Latin is an inflected language, their forms in sentences bear no resemblance to their English counterparts. Typically, a Latin adjective follows the noun it modifies. To explain this, many Latin programs tell the student to think of it this way: A noun is more important than an adjective that modifies or characterizes it. This is why a noun comes before an adjective in Latin. This contrasts to English, in which adjectives normally appear before the nouns they modify.

    Group Two adjectives consist only of adjectives of the third declension. This fact is deceptively simple in contrast to Group One adjectives, which consist of adjectives from the two previous declension. This deception derives from the fact that Group Two adjectives break down further into three subcategories. If there were ever a time to emphasize the need to memorize all the forms of an adjective, this would be it. Identifying to which subcategory an adjective belongs depends on how many nominative singular case forms it has. To some Latin students, the need to memorize the forms of Group One adjectives seems unnecessary as they follow regular patterns with a few exceptions. However, this practice in the early part of a student’s study makes it much easier for a student to learn Group Two adjectives.

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    Two Form Adjectives

    The most common subcategory of Group Two adjectives are those known as two-form adjectives. They are so called because they have only two nominative forms; one for masculine and feminine forms and one for the neuter form. In other words, two-form adjectives share the same nominative singular form for both masculine and feminine adjectives and there is a separate nominative singular form for neuter adjectives. The Latin word “fortis" is an example of a two-form adjective. Its declension looks like this:

    Singular

    nom. fortis, forte

    gen. fortis, fortis

    dat. forti, forti

    acc. fortem, forte

    abl. forti, forti

    Plural

    nom. fortes, fortia

    gen. fortium, fortium

    dat. fortibus, fortibus

    acc. fortes, fortia

    abl. fortibus, fortibus

    Notice that since the masculine and feminine genders have the same form, it is unnecessary to repeat them. The neuter form of the adjective, with its separate nominative singular form, is declined fully above.

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    One Form Adjectives

    The second most common Group Two adjectives are those of the one-form variety. They are called one-form adjectives because all three genders share the same form throughout the nominative singular case. The word “potens" is an example of a one-form adjective. Its declension looks like this:

    Singular

    nom. potens, potens

    gen. potentis, potentis

    dat. potenti, potenti

    acc. potentem, potens

    abl. potenti, potenti

    Plural

    nom. potentes, potentia

    gen. potentium, potentium

    dat. potentibus, potentibus

    acc. potentes, potentia

    abl. potentibus, potentibus

    Notice that the masculine, feminine, and neuter nominative case all have the characteristic similar nominative singular form of a one-form adjective.

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    Three Form Adjectives

    Not surprisingly, three-form adjectives have three separate forms in the nominative singular for each of the three genders. These adjectives are the least common of the Group Two adjectives. The word “acer" is an example of a three-form adjective. Its declension looks like this:

    Singular

    nom. acer, acris, acre

    gen. acris, acris, acris

    dat. acri, acri, acri

    acc. acrem, acrem, acre

    abl. acri, acri, acri

    Plural

    nom. acres, acres, acria

    gen. acrium, acrium, acrium

    dat. acribus, acribus, acribus

    acc. acres, acres, acria

    abl. acribus, acribus, acribus

    Notice that there is a separate nominative singular form for each of the three genders characteristic of three-form adjectives.

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    Conclusion

    Although Group Two adjectives consist of adjectives from only the third declension, their three subcategories make them far more complicated than those adjectives of Group One. The key to identifying whether a Group Two adjective is of the one-, two, or three-form variety is in the number of nominative singular forms it has. Notice that although the word “potens" is a two-form adjective, it still takes two columns to decline it fully; it needs one column for the masculine and feminine forms and a separate column for the neuter forms. A Group Two adjective belongs to a subcategory because of its number of nominative singular forms only, not because of the number of columns needed to decline it fully. This fact gives students trouble when they expect Group Two adjectives to behave like those of Group One.

Latin Adjectives of the First, Second, and Third Declensions

Latin adjectives can be categorized into two major groups. Group One consists of adjectives of the first and second declension and Group Two consists of the adjectives of the third declension. This grouping makes it easier for the Latin students to identify an adjective and use it properly.
  1. How to Form Latin Adjectives of the First and Second Declension
  2. How to Form Latin Adjectives of the Third Declension