labile
adjective·/ˈleɪ.baɪl/
1. Unstable; readily altered, shifted, or broken down. Said of emotions, chemical compounds, or systems that do not hold their form for long (technical; also general). Where fragile means easy breakage, labile means easy change.
After the shock, her mood was labile—laughter and tears exchanging places with bewildering speed.
2. In chemistry and biology, prone to rapid transformation or decomposition under given conditions (technical).
The solution was too labile to store; by morning it had already become something else.
Etymology
From Latin labilis “prone to slip,” from labi “to slip, fall.” Instability as a tendency to slide.
Related Words
volatilequick to change; often more explosive in feel
metastablestable for a time, then prone to shift
mutablechangeable; less technical in tone
inconstanthuman-centered synonym