(chemistry) A quaternary compound. / (geology) The Quaternary period or the system of deposits laid down during it.

Of fourth rank or order / Of a mathematical expression containing e.g. x⁴ / Relating to or in number base four / (organic chemistry) quaternary ammonium / (inorganic chemistry) composed of four elements

(geology) The geological period of the Cenozoic Era immediately following the Tertiary. It is subdivided into the Pleistocene and the Holocene Epochs.

plural of quaternary

The sector of industry that involves the intellectual services: research, development, and information. It is considered the fourth basic industry.

(chemistry) An ammonium group in which each hydrogen has been replaced by an alkyl or aryl group

(biochemistry, molecular biology) The arrangement of multiple folded or coiled proteins to form a multi-subunit complex.

Synonym of quaternary care

(medicine) Highly specialized healthcare treatments, such as experimental medicine and uncommon surgical procedures.

(chemistry) A cation consisting of a central positively-charged nitrogen atom with four substituents, especially organic (alkyl and aryl) groups, discounting hydrogen atoms.