an unstable order
"The sudden political instability left the country without a functioning government for months."
unreliability attributable to being unstable
"The new engine showed significant instability, causing it to fail repeatedly under heavy load."
the quality or attribute of being unstable and irresolute
"His political instability made it impossible for voters to trust him as a consistent leader."
The quality of being unstable.
"The political instability in the region made it difficult for tourists to plan their trips."
In plain English: Instability is when something keeps shaking, changing, or falling apart instead of staying steady and safe.
"The political instability in the region has caused many people to flee their homes."
The word instability comes from Middle French and ultimately Latin, where it originally meant the state of being unstable. It entered English as a direct borrowing to describe a condition lacking firmness or steadiness.