noun, noun which may take the genitive case particle 'no'
Refers to the tendency of a substance to vaporize; also used figuratively for unstable situations or emotions.
この液体は揮発性が高いので、密閉容器に保管してください。
This liquid is highly volatile, so please store it in a sealed container.
市場の揮発性が高まっている。
Market volatility is increasing.
不安定 means 'unstable' in a general sense, whereas 揮発性 specifically implies volatility, often with a chemical or financial nuance.
Compound of 揮発 (volatilization) + 性 (property, nature). 揮発 is from 揮 (wave, brandish) and 発 (emit, discharge).