'Irreversibility' definitions:

Definition of 'irreversibility'

From: WordNet
noun
The quality of being irreversible (once done it cannot be changed) [ant: reversibility]

Definition of 'Irreversibility'

From: GCIDE
  • Irreversibility \Ir`re*vers`i*bil"i*ty\, n. The state or quality of being irreversible; irreversibleness. [1913 Webster]