1. superlative form of unstable; most likely to change, fail, or give way; least steady or secure
Usage: superlative form; formal

Examples

• The unstablest part of the old bridge collapsed during the storm.
• Among all the chemical compounds tested, this one proved to be the unstablest.
• The unstablest patients were moved to the intensive care unit.
• This is the unstablest political situation the country has faced in decades.
• The unstablest ground conditions were found near the riverbank.