|a screen or mat covered with a dark material for shielding a camera lens from excess light or glare.|
|a fool or simpleton; ninny.|
|1.||consisting of fours or by fours|
|2.||fourth in a series|
|3.||chem containing or being an atom bound to four other atoms or groups: a quaternary ammonium compound|
|4.||maths having four variables|
|—n , -naries|
|5.||the number four or a set of four|
|[C15: from Latin quaternārius each containing four, from quaternī by fours, distributive of quattuor four]|
quaternary qua·ter·nar·y (kwŏt'ər-něr'ē, kwə-tûr'nə-rē)
Consisting of four; in fours.
Relating to an atom bonded to four carbon atoms.
|quaternary (kwŏt'ər-něr'ē) Pronunciation Key
Noun Quaternary. The second and last period of the Cenozoic Era, from about 2 million years ago to the present. During this time the continents were situated approximately as they are today, although the geography was different due to fluctuations in sea levels caused by the advance and retreat of ice sheets. Humans first appeared during this period. See Chart at geologic time.
Adjective Relating to or having a carbon atom that is attached to four other carbon atoms in a molecule. Quaternary pentane, for example, contains five carbon atoms of which one is in the center and the other four are each attached to it.