Here's a breakdown:

* Ir-: A prefix meaning "not" or "opposite of."

* Reversible: Capable of being reversed or changed back to its original state.

So, putting it together, "irreversible" means "not reversible" or "impossible to reverse."

Examples:

* Time is irreversible. You can't go back in time.

* The damage to the car was irreversible. The car was too badly damaged to be repaired.

* The decision was irreversible. Once made, the decision could not be changed.

Here are some synonyms for irreversible:

* Permanent

* Unchangeable

* Inalterable

* Final

* Conclusive

Let me know if you'd like any further clarification or examples!