On an average

Also found in: Idioms.
taking the mean of unequal numbers or quantities.

See also: Average

References in classic literature ?
A plant which annually produces a thousand seeds, of which on an average only one comes to maturity, may be more truly said to struggle with the plants of the same and other kinds which already clothe the ground.
It would suffice to keep up the full number of a tree, which lived on an average for a thousand years, if a single seed were produced once in a thousand years, supposing that this seed were never destroyed, and could be ensured to germinate in a fitting place.
ON's error also resulted in around 500 prepayment customers for the January 2013 price increase and around 6,500 for the January 2014 increase missing out on an average refund of PS3.