A mezzo-soprano (/ˈmɛtsoʊ/; [ˈmɛddzo]; meaning "medium" or "middle" "soprano" in Italian) is a type of classical female singing voice whose range lies between the soprano and the contralto singing voices, usually extending from the A below middle C to the A two octaves above (i.e. A3-A5 in scientific pitch notation, where middle C = C4). In the lower and upper extremes, some mezzo-sopranos may extend down to the G below middle C (G3) and as high as "high C" (C6).[1]

from Mr Wikipedia