Two common types of requests that we get are (1) how to construct hypothetical vernacular forms of names when our only evidence is Latin documentary forms, and (2) the other way around: How to construct a plausible Latinized form of a name in a vernacular. In this post, we provide some background for answering both of these questions in the form of some basic Latin grammar recap.
Latin is a case-based language, meaning that a single word can occur in different grammatical forms depending on how it is used in a sentence. (English used to be a case-based language, but it has lost many of the distinctions of case over time. A few remain: The difference between, e.g., the standard form “John” and the possessive form “John’s”, or the difference between, e.g., ‘she’, ‘her’, and ‘hers’.) The six cases, and the grammatical contexts in which they are used, are:
- Nominative: Used for the subject of a sentence.
- Genitive: Used to indicate ownership or possession.
- Dative: Used for indirect objects, and with certain prepositions.
- Accusative: Used for direct objects.
- Ablative: Used with certain prepositions, usually ones indicating movement ‘away’ or ‘from’.
- Vocative: Used when identifying a person or thing being addressed.
Note that we are vastly oversimplifying here: In particular, the oblique forms (that is, the non-nominative ones) are much more complex in when and how they are used.
Because names can be found in any of these six different grammatical contexts, they can be found in any of these cases. The case that a word (including names) is in can be determined by a combination of the ending of the word and the grammatical context it is in. (For example, when the dative and the ablative forms of a word are identical, the presence of a preposition used with the ablative case can identify which case the word is.) The case endings generally follow a reliable pattern depending on which declension a word is in, and the part of the word to which the case ending is added is called the stem. Latin has five declensions, of which most names fall in the first three, so they’re the ones we’ll focus on:
Words in the first declension have fixed stems and the following case endings (in the singular):
Most feminine names are in the first declension.
Words in the second declension have fixed stems and the following case endings (in the masculine singular):
Most masculine names are in the second declension. (The second declension also contains words of neuter gender, which have the ending -um in the nominative, but they are not relevant for our purposes: Personal names in medieval records are always either masculine or feminine in grammatical gender.)
Words in the third declension have stems that change when an oblique case ending is added. Typically, these case endings are:
However, in some cases, the accusative form of a third declension name is identical with the nominative; and there are a variety of other slight variations amongst third declension names. Many masculine names whose nominative form ends in -o Hugo) are third declension.
In part 2 of this series, we’ll look at how one can take a name in Latin, whether nominative or oblique, and, comparing it with other Latin-vernacular pairs of similar declension and case, hypothesize plausible vernacular forms.
 Classical Latin -ae often was reduced to -e in medieval Latin.