Surd

a.	1.	Net having the sense of hearing; deaf.
	2.	Unheard.
	3.	(Math.) Involving surds; not capable of being expressed in rational numbers; radical; irrational; as, a surd expression or quantity; a surd number.
	4.	(Phonetics) Uttered, as an element of speech, without tone, or proper vocal sound; voiceless; unintonated; nonvocal; atonic; whispered; aspirated; sharp; hard, as f, p, s, etc.; - opposed to sonant. See Guide to Pronunciation, 169, 179, 180.
n.	1.	(Math.) A quantity which can not be expressed by rational numbers; thus, ?2 is a surd.
	2.	(Phon.) A surd element of speech. See Surd, a., 4.

Noun	1.	surd - a consonant produced without sound from the vocal cords Synonyms: voiceless consonant
Adj.	1.	surd - of speech sounds Synonyms: unvoiced, voiceless Antonyms: sonant, voiced - of speech sounds

Gaussian integer, accented, algebraic number, algorismic, algorithmic, aliquot, allophone, alveolar, apical, apico-alveolar, apico-dental, articulated, articulation, aspiration, assimilated, assimilation, back, barytone, bilabial, broad, cacuminal, cardinal, cardinal number, central, cerebral, check, checked, close, complex number, consonant, consonantal, continuant, deaf, deaf and dumb, deaf-eared, deaf-mute, deafened, decimal, defective number, dental, differential, digital, diphthong, dissimilated, dissimilation, dorsal, dull-eared, earless, epenthetic vowel, even, even number, explosive, exponential, figural, figurate, figurative, finite, finite number, flat, fraction, fractional, front, glide, glossal, glottal, glottalization, guttural, hard, hard of hearing, heavy, high, imaginary, imaginary number, impair, impossible, infinite, infinity, integer, integral, intonated, irrational, irrational number, labial, labialization, labiodental, labiovelar, laryngeal, lateral, lax, light, lingual, liquid, logarithmic, logometric, low, manner of articulation, mid, mixed number, modification, monophthong, monophthongal, morphophoneme, mute, muted, narrow, nasal, nasalized, negative, numeral, numerary, numerative, numeric, occlusive, odd, open, ordinal, oxytone, pair, palatal, palatalized, parasitic vowel, peak, pharyngeal, pharyngealization, pharyngealized, phone, phoneme, phonemic, phonetic, phonic, pitch, pitched, plosive, polygonal number, positive, possible, posttonic, prime, prime number, prothetic vowel, pure imaginary, radical, rational, rational number, real, real number, reciprocal, rectangular number, retroflex, round number, rounded, segmental phoneme, semivowel, serial number, soft, sonant, sonority, speech sound, stone-deaf, stop, stopped, stressed, strong, stunned, submultiple, syllabic, syllabic nucleus, syllabic peak, syllable, tense, thick, thick of hearing, throaty, tonal, tone-deaf, tonic, transcendental, transcendental number, transfinite number, transition sound, triphthong, twangy, unaccented, unhearing, unrounded, unstressed, velar, vocable, vocalic, vocoid, voice, voiced, voiced sound, voiceless, voiceless sound, voicing, vowel, vowellike, weak, whole number, wide, word-deaf