All 8 Uses of

factor
in
War and Peace

In military affairs the strength of an army is the product of its mass and some unknown x. Military science, seeing in history innumerable instances of the fact that the size of any army does not coincide with its strength and that small detachments defeat larger ones, obscurely admits the existence of this unknown factor and tries to discover it—now in a geometric formation, now in the equipment employed, now, and most usually, in the genius of the commanders.†
Chpt 14

factor = thing that affects a result or outcome

To define and express the significance of this unknown factor—the spirit of an army—is a problem for science.†
Chpt 14

This equation does not give us the value of the unknown factor but gives us a ratio between two unknowns.†
Chpt 14 *

That a criminal was reared among male factors mitigates his fault in our eyes.†
Chpt 15

factors = things that affect a result or outcome

But the assignment of these various meanings to the factor does not yield results which accord with the historic facts.†
Chpt 14

The spirit of an army is the factor which multiplied by the mass gives the resulting force.†
Chpt 14

This problem is only solvable if we cease arbitrarily to substitute for the unknown x itself the conditions under which that force becomes apparent—such as the commands of the general, the equipment employed, and so on—mistaking these for the real significance of the factor, and if we recognize this unknown quantity in its entirety as being the greater or lesser desire to fight and to face danger.†
Chpt 14

Only then, expressing known historic facts by equations and comparing the relative significance of this factor, can we hope to define the unknown.†
Chpt 14

Definitions:

(1) (factor as in: It was the deciding factor.)
something that affects a result or outcome

You also may encounter x-factor or x factor--meaning "the most important thing that influences a result or outcome."
(2) (factor as in: factor it into your thinking)
include consideration of
(3) (meaning too rare to warrant focus)
meaning too rare to warrant focus:

See a comprehensive dictionary for other meanings. Less common meanings include one that has to do with units of measurement. More specialized meanings are used in fields including mathematics, business, finance, biology, and grammar.