irreversible

Everyday

Not able to be changed back to how it was before. tree →

In the lessons

In science lessons on changes of materials: burning, cooking an egg and rusting are irreversible changes; melting ice is reversible. Also in health and environment (irreversible damage). Phrases: irreversible change, irreversible damage.

Examples

• Baking a cake is an irreversible change. tree →
• Burning paper is irreversible. tree →
• Melting chocolate is reversible but burning it is irreversible. tree →
• Extinction is irreversible: the dodo is gone forever. tree →
• Some hearing damage is irreversible, so turn the music down. tree →
• The decision was irreversible. tree →

Note

Opposite: reversible. Science: an irreversible change usually makes a new material; a reversible change (melting, freezing, dissolving) does not.