Both Uses

factor
in
The Princess Bride
(Auto-generated)

But there was no dealing with the wizard, and slowly, again, the deadly Cliffs became a factor in the fight, only now it was the man in black who was being forced to doom.†
p. 150.5

factor = thing that affects a result or outcome
As an architect, he had been crucial in the safety factors involved in the Zoo of Death, and it had undeniably been Rugen who had arranged for the only survivable entrance being the underground fifth-level one.†
p. 254.4 *

factors = things that affect a result or outcome

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)
There are many specialized meanings in fields such as mathematics, business, finance, biology, and grammar.