from
The Collaborative International Dictionary of English v.0.48
Slugging average \Slug"ging av`er*age\ (Baseball)
a measure of the effectiveness of a batter at reaching base
and advancing other runners, calculated as the sum of the
number of bases reached on each hit, divided by the total
number of times at bat. A double counts two bases, a triple
three, a home run four. Thus a batter with four singles, two
doubles and a triple in 20 official times at bat would have a
slugging average of 0.550, and a {batting average} of 0.350.
Also called {slugging percentage}. Compare {batting average}.
[PJC]