1.  contralto(n = noun.person) - a woman singer having a contralto voice;
is a kind of singer, vocaliser, vocalist, vocalizer
has particulars: anderson, marian anderson, ernestine schumann-heink, schumann-heink

2.  contralto(n = noun.communication) alto - the lowest female singing voice;
is a kind of singing voice

   contralto(s = adj.all) alto - of or being the lowest female voice;

   The part sung by the highest male or lowest female voices; the alto or counter tenor. [1913 Webster]
" The usual range of the contralto voice is from G, below middle C, to the C above that; though exceptionally it embraces two octaves." [1913 Webster]

   Of or pertaining to a contralto, or to the part in music called contralto; as, a contralto voice. [1913 Webster]

contralto, n. (pl. -os)
1 a the lowest female singing-voice. b a singer with this voice.
2 a part written for contralto.

Etymology:
It. (as CONTRA-, ALTO)

N  resonance, ring, ringing, tintinabulation, reflexion, reflection, reverberation, echo, reecho, zap, zot, buzz (hiss), low note, base note, bass note, flat note, grave note, deep note, bass, basso, basso profondo, baritone, barytone, contralto, echo chamber, resonator, tinnitus, bell, doorbell, buzzer, gong, cymbals (musical instruments), sympathetic vibrations, natural frequency, coupled vibration frequency, overtone, resonating cavity, sounding board, tuning fork, tuning, squelch, frequency selection, resonator, resonator circuit, radio resonant structure, aromaticity, alternating double bonds, non-bonded resonance, pi clouds, unsaturation, double bond, (valence), resounding, resonant, reverberant, tinnient, tintinnabulary, sonorous, booming, deep-toned, deep-sounding, deep-mouthed, vibrant, hollow, sepulchral, gruff, sweet bells jangled, out of time and harsh, echoing down the mountain and through the dell.