Does Latin require two words to name things?

Answer 1

I can think of two reasons why you might ask this question. The first is that living things are sometimes referred to by two-part names, often with Latin roots. These so-called "Linnaean binomials" shouldn't be confused with the "Latin names" of these living things; they are modern inventions devised by scientists according to a system developed in the 1700's by the Swedish biologist Carl von Linné.

Linnaean binomials (Homo sapiens, Australopithecus afarensis, Felis catus) are often derived from Latin, but not necessarily so. Australopithecus afarensis, for example, actually incorporates components from three languages: Latin, Greek and Afar (a language of northeast Africa). Even when a binomial is of purely Latin origin, however, that doesn't mean that it's the "Latin name" of the species. Scientists may call humans Homo sapiens and cats Felis catus, but to the Romans they were simply homo and feles respectively.

Alternatively, you may be referring to the fact that Latin nouns are often cited in two forms. For example, you may have read somewhere that the Latin word for "light" is "lux lucis". This doesn't mean that the word for light is literally the two-word phrase "lux lucis". What it does mean is that, in Latin, the form of a noun varies depending on how it's used in a sentence, and in order to know all the possible forms a given noun can take, you need more than one piece of information. Specifically, you need to know three things:

1. the nominative singular - the form the noun takes as the subject of a sentence
2. the genitive singular - the possessive ("of the ") form
3. the gender - whether the noun is masculine, feminine or neuter

Lux is the nominative singular of the word for "light"; lucis is the genitive singular. From these two forms, and the information that the word is feminine (actually, that it's not neuter), we can derive all of its forms:

Singular:

• Nominative: lux ("[a/the] light": subject form)
• Genitive: lucis ("of [a/the] light")
• Dative: luci ("to/for [a/the] light")
• Accusative: lucem ("[a/the] light": object form)
• Ablative: luce ("by/from/with [a/the] light")

Plural:

• Nominative: luces ("[the] lights": subject form)
• Genitive: lucum ("of [the] lights")
• Dative: lucibus ("to/for [the] lights")
• Accusative: luces ("[the] lights": object form)
• Ablative: lucibus ("by/from/with [the] lights")