quaternary

Pronunciation: kwah′tĕr-nār′ē, kwah-tĕr′nĕ-rē

Definition:

1. Denoting a chemical compound containing four elements; NaHSO₄.
2. Fourth in a series.
3. Relating to organic compounds in which some central atom is attached to four functional groups; applied to the usually trivalent nitrogen in its “onium” state, R₄N+, “quaternary nitrogen.”
4. Referring to a level of structure of macromolecules in which more than one biopolymer is present.

[L. quaternarius, fr. quaterni, four each, fr. quattuor, four, + -arius, adj. suffix]

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