:Binary feature:

Pronunciation ˈbaɪnəri

A property which is used to classify a linguistic form in terms of two opposite values. In phonetics and phonology, for example, units may be specified as [+high] or [-high], depending on whether the body of the tongue is raised or not. Various inventories of phonetic binary features have been proposed. Some are based on acoustic properties, some on articulatory properties and some on a mixture of the two.

See also element, n-ary feature.