§92. General Principles of Latin Compounds

Most Latin compound words and their derivatives can be divided into two classes:

• In DESCRIPTIVE compounds, the first element (usually an adjective) describes the second (usually a noun). A good example is aequ-i-libr-ium (E equilibrium), where the first base is the adjective aequus (“even”) and the second is the noun libra (“balance”). Another is mult-i-later-alis (E multilateral), where the first base is the adjective multus (“many”) and the second is the noun latus, lateris (“side”). The English compound adjective many-sided corresponds closely to multilateral. 
• In DEPENDENT compounds, the first element (typically a noun or adjective) is dependent on the second (usually a verb). For example, carn-i-vor-a (E carnivora, carnivores) are “eaters of flesh,” and a con-i-fer (E conifer) is a “bearer of cones.”

It doesn’t seem very profitable deciding whether a Latin compound is descriptive or dependent, since we don’t worry about these academic distinctions in English (where housemaid is descriptive, but housecleaner dependent; homemade descriptive, but homemaker dependent). In practical terms, it is more important to observe how Latin compounds are formed: the two bases are linked by a CONNECTING VOWEL, almost always -i-. That is a principle that was followed throughout the history of Latin, and is still observed today when new Latin loan-words are coined in science or medicine. In some old Latin compounds—especially numerical compounds—a different connecting vowel can be seen, like the -u- in quadr-u-ped (“four foot”). Normally, however, it will be -i-. No such vowel is needed if there is already a vowel at the juncture of the two bases; therefore magn-anim-us (E magnanimous), “great-spirited,” aequ-anim-itas (E equanimity), “level-mindedness,” and bene-fact-or (“well-doer”).