Latin: an inflected language
Inflection
One of the most striking differences between Latin and English is how Latin changes the form of words to indicate their function in a sentence, where English uses word order. We call this systematic change in forms inflection.
English has only limited grammatical inflection today, but most English nouns have different forms indicating whether they are singular or plural: “dog” means only one, but “dogs” means more than one. Adding an -s to a noun is a regular pattern in English. We could say that -s is the regular inflectional ending to indicate the grammatical property of number for a noun.
Aside: English is related to Latin as part of the larger IndoEuropean family of languages, and in earlier phases of its history had a much fuller system of inflection, comparable to Latin.
In the present tense, English verbs in the third person singular (he, she, it) also change form to indicate number: “she says” but “they say.” We use singular verb forms only with singular subjects, and plural verb forms with plural subjects: “The dogs run,” but “The dog runs.”
Some English nouns change their form in less predictable ways: “mouse” is a singular noun, and “mice” is plural. Native speakers learn this without thinking about it; people who learn English as a second language have to memorize this as an exception to the regular pattern of adding -s to form plurals.
A few English nouns do not change their form to indicate number. “Moose” could refer to one or more of the largest mammal in the deer family. (And “deer” poses the same problem: one or more?) A native speaker of English can say, “The moose walks,” and “The moose walk.” The verb makes it clear that in the first sentence, “moose” is singular, but plural in the the second sentence.
Function and form
Like English, Latin uses inflection to show the number of nouns and verbs, but Latin’s system of inflection far more extensive than English.
English, for example, follows a strict word order to indicate subject, verb and direct object of a sentence. “Dog bites man” is an everyday sentence: the subject is “Dog,” and the direct object is “man.” “Man bites dog” is a headline: the man is now doing the biting, and dog is the recipient of the action.
Latin most frequently (but not always) places the verb at the end of a sentence. You could equally comfortably have a three-word sentence in the order Object-Subject-Verb, or Subject-Object-Verb, because the inflected form of the subject and the object will show clearly what role each word plays.
Aside You will probably never find the order English requires: Subject-Verb-Object! When we read Latin, and we practice our skills with Latin composition, we’ll want to consider what nuance or emphasis is expressed through different choices of Latin’s more flexible word order.
See the following introduction to inflection from Dominic Machado for Latin examples drawn from Hyginus’ Fabulae of how Latin inflection can work>