noun
reversibility
Technical term used in physics, chemistry, and engineering to describe processes or reactions that can proceed in both directions.
この化学反応は可逆性がある。
This chemical reaction has reversibility.
可逆性の原理は熱力学で重要だ。
The principle of reversibility is important in thermodynamics.
不可逆性 means 'irreversibility', the opposite property.
Compound of 可逆 (reversible) + 性 (-ity, property). The exact historical derivation is uncertain, but it follows a common pattern for forming abstract nouns from adjectives.