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035. A series of mechanical improvements continuing well into the nineteenth century,  including the introduction of pedals to sustain tone or to soften it, the perfection of a metal  frame, and steel wire of the finest quality, finally produced an instrument capable of  myriad tonal effects from the most delicate harmonies to an almost orchestral fullness of  sound, from a liquid, singing tone to a ship, percussive brilliance.  The word "myriad" is closest in meaning to which of following?