| the mean obtained by taking the reciprocal of the arithmetic mean of the reciprocals of a set of nonzero numbers. |

| harmonic mean n. The reciprocal of the arithmetic mean of the reciprocals of a specified set of numbers. |
harmonic mean har·mon·ic mean (här-mŏn'ĭk)
n.
The reciprocal of the arithmetic mean of the reciprocals of a specified set of numbers.