earned run average

noun Baseball.
  1. a measure of the effectiveness of a pitcher, obtained by dividing the number of earned runs scored against the pitcher by the number of innings pitched and multiplying the result by nine. A pitcher yielding three earned runs in nine innings has an earned run average of 3.00. Abbreviation: ERA, era

Origin of earned run average

First recorded in 1945–50
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018