The Collaborative International Dictionary of English v.0.48:

Irremeable \Ir*re"me*a*ble\, a. [L. irremeabilis; pref. ir- not
   + remeabilis returning, fr. remeare: cf. F. irr['e]m['e]able.
   See Remeant.]
   Admitting no return; as, an irremeable way. [Obs.] --Dryden.
   [1913 Webster]