(1) A term used in the phonological classification of vowel sounds, referring to a vowel which can be analysed as a centralized variant of a vowel in a related form.
(2) A future phonological use of the term is found in the context of phonological rules, where it refers to a process of simplification which affects certain types of sound sequence. The most important category is consonant-cluster reduction.
(3) In grammar, the term usually refers to a clause which lacks one or more of the elements required to enable it to be used as a full, independent construction. Such clauses may be referred to as ‘abbreviated’, elliptical, or contracted; but different approaches often introduce distinctions between these terms. Other units are sometimes referred to as ‘reduced’, such as phrases and words.