Univocal terms are words, such as entomology, that precisely describe one idea. Equivocal terms are words like chihuahua, both a dog and a city, that have multiple distinct meanings. Analogous terms are metaphors, such as "worm," which refers to the animal or a suspicious person.
A univocal term is a word that both correctly and precisely describes exactly one idea. This type of word always corresponds to exactly one definition. Language is flexible and ever-evolving, so univocal words may become equivocal words over time. Other times, a word is thought to be univocal, but a secondary meaning is discovered, causing it to become equivocal.
Equivocal terms are words that contain more than one meaning and therefore correspond to multiple definitions. The intent of an equivocal word changes completely depending on which definition a user applies. A nut, for example, refers to the food, the mechanical tool and a foolish or insane person. Equivocal terms and analogous terms often overlap.
Analogous terms are those which apply to two different things that both have something in common and something that separates the two terms. The term "backup," which refers both to a computer backup and police backup, is an example of two similar but different terms using the same word.