Each of the sets forming a direct product is said to be a direct factor. A group 
is said to be a direct factor of the group 
if 
is isomorphic to the group
direct product 
for some group 
.
In the case of Abelian groups, 
is isomorphic to the direct
sum 
,
and direct factor is a synonym for direct summand.
Direct Factor
See also
Direct Product, Direct Sum, Direct Summand, Group Direct ProductThis entry contributed by Margherita Barile
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Barile, Margherita. "Direct Factor." From MathWorld--A Wolfram Web Resource, created by Eric W. Weisstein. https://mathworld.wolfram.com/DirectFactor.html