The word stability comes from the Latin word stabo;otas (firmness or a standing fast), derived from stabilis (firm or steadfast).  This traces back to the Latin verb stare ("to stand") and the Proto-Indo-European root *steh₂-, which also gives English words like stand, stage, and stay.  It entered Middle English in the 14th century via Old French (stabilite / establete).  

According to the Oxford English Dictionary (OED), the noun stability was first used in English during the Middle English period (1150-1500), with the earliest recorded evidence dating from before 1400.  At first, the word applied to political and social groups to mean a government or society that stays strong and safe.  By the early 1500s it was used for physical objects to describe things that are hard to knock over or push down.  By the 1540s it came to mean staying the exact same way over time.  

Stability in storytelling provides a baseline of normalcy, anchoring the audience and giving contrast to conflict.   It establishes a foundation of trust, creates clear context, and makes the eventual stakes and changes meaningful.  

Why Stability Matters:  
Creates Contrast: Change and chaos only feel dramatic when measured against a stable starting point (the "status quo").  
Builds Trust: A stable narrative structure or predictable baseline helps the audience feel safe to explore difficult or chaotic themes.  
Provides Context: Ground rules of the world or character baseline behavior explain why an event is disruptive.  
Aids Meaning: Psychological continuity in character growth requires a stable core identity to measure transformation against.  
Can be a Goal:  It can also become a goal for characters lacking stability in their lives.