voiceless

adj. without a voice; silent; having no opinion; without influence; having no vote

In phonetics, voice or voicing is one of the three major parameters used to describe a sound. It is usually treated as a binary parameter with sounds being described as either voiceless (unvoiced) or voiced, although in fact there can be degrees of voicing (see below).A voiced sound is one in which the vocal cords vibrate, and a voiceless sound is one in which they do not. Voicing is the difference between pairs of sounds such as and in English. If one places the fingers on the voice box (ie the location of the Adam's apple in the upper throat), one can feel a vibration when one pronounces zzzz, but not when one pronounces ssss. (For a more detailed, technical explanation, see phonation.)
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Adjective
1. of speech sounds
(synonym) surd, unvoiced
(classification) linguistics
2. not using the voice; "unvoiced thoughts"; "unvoiced consonants such as `p' and `k' and `s'"
(synonym) unvoiced
(similar) whispered
3. uttered without voice; "could hardly hear her breathed plea, `Help me'"; "voiceless whispers"
(synonym) breathed
(similar) inaudible, unhearable
4. being voiceless through injury or illness and thus incapable of all but whispered speech
(synonym) aphonic
(similar) inarticulate, unarticulate

(a.)
Not sounded with voice; as, a voiceless consonant; surd.
  

(a.)
Having no voice, utterance, or vote; silent; mute; dumb.
  

Synonyms and related words:
accented, alveolar, anaudic, aphasic, aphonic, apical, apico-alveolar, apico-dental, articulated, assimilated, back, bad, bare, barytone, bereft, bilabial, breathless, broad, cacuminal, central, cerebral, checked, close, consonant, consonantal, continuant, dental, denuded, deprived, destitute, dissimilated, dorsal, dumb, dumbfounded, dumbstricken, dumbstruck, empty, flat, front, glide, glossal, glottal, guttural, hard, heavy, high, inarticulate, innocent, intonated, invalid, labial, labiodental, labiovelar, lateral, lax, light, lingual, liquid, low, mid, monophthongal, mum, mute, muted, narrow, nasal, nasalized, null and void, occlusive, open, oxytone, palatal, palatalized, pharyngeal, pharyngealized, phonemic, phonetic, phonic, pitch, pitched, posttonic, retroflex, rounded, scant, semivowel, short, shy, soft, sonant, speechless, stopped, stressed, stricken dumb, strong, surd, syllabic, tense, thick, throaty, tonal, tongue-tied, tongueless, tonic, twangy, unaccented, unrounded, unstressed, velar, vocalic, vocoid, voiced, vowel, vowellike, weak, wide, wordless