2. (adj)fricative, continuant, sibilant, spirant, strident of speech sounds produced by forcing air through a constricted passage (as `f', `s', `z', or `th' in both `thin' and `then')
Definition of 'spirant'
Webster Dictionary
1. (noun)spirant a term used differently by different authorities; -- by some as equivalent to fricative, -- that is, as including all the continuous consonants, except the nasals m, n, ng; with the further exception, by others, of the liquids r, l, and the semivowels w, y; by others limited to f, v, th surd and sonant, and the sound of German ch, -- thus excluding the sibilants, as well as the nasals, liquids, and semivowels. See Guide to Pronunciation, // 197-208
Definitions of spirant 
