1. Relating to or composed of several names or terms.
2. In biology, a taxonomic designation having more than two terms. or names of plants or animals consisting of descriptive phrases of more than three words, as those in use before binomial nomenclature.
3. A mathematical expression of two or more terms.

Used to describe a mathematical expression that has more than two terms, or a system of taxonomic nomenclature that uses more than two names.