Substitution
The act of replacing one thing, person, or element with another, often following a formal process or set rules.

Substitution is the act of replacing one thing, person, or element with another, typically following established rules or a formal process. It originates from the Latin 'substituere,' meaning to set under or stand in place of, and applies broadly across fields like chemistry (replacing atoms), law (substituting a party), and sports (replacing a player).
What this means in real life
A baker runs out of butter mid-recipe and uses coconut oil instead—that's substitution. Or when someone angry at their boss goes home and snaps at their partner instead, they're unconsciously substituting the target of their frustration.
What it isn’t
Substitution is not the same as compromise or negotiation. It's not about finding middle ground or both parties giving something up; it's simply replacing one thing entirely with another.
Commonly misused online
People often use 'substitution' to mean 'temporary fix' or 'inferior replacement,' but substitution is neutral—the replacement can be equal, better, or worse depending on context.