cause, factor, be associated with, depend on, be limited to
因 centers on the idea of a cause or underlying factor that something else depends on or is associated with. The sense of being limited to something follows naturally from being tied to a specific cause.
因 originally depicted a person (大) on a mat or within an enclosure, suggesting dependence or reliance, which developed into the abstract idea of cause or factor.
A big person (大) is enclosed (囗) and cannot move freely. Their situation is the cause of their limitation, and everything they do depends on that factor.
For イン, imagine the big person inside the enclosure is an innkeeper: inn -> イン, and the inn is the cause of their livelihood.
cause; origin; source
by the way; in this connection; incidentally; in passing
main cause; primary factor
cause of death
to be associated (with); to be connected (with)
factor
cause and effect; causality
to be caused by; to result from; to arise from; to stem from; to be due to
one cause; one reason; one factor
cause; factor
fate; destiny
association; link; connection
cause of defeat
retribution; retributive justice; karma; just deserts; poetic justice; reward and punishment for one's past behavior
Inaba (former province located in the east of present-day Tottori Prefecture)
remote cause; underlying cause; indirect cause
contributing cause; exciting cause; incentive; motive
primary cause; main factor
factor
convention; tired tradition; old custom