Webster's Revised Unabridged Dictionary
L. irremeabilis,; pref. ir-, not + remeabilis, returning, fr. remeare,: cf. F. irréméable,. See Remeant
Chambers's Twentieth Century Dictionary
L. in, not, remeabilis, remeāre—re, back, meāre, to go, come.
The keeper charm'd, the chief without delay Pass'd on, and took th' irremeable way.
"The Aeneid" by Virgil
The unusual though expressive term "irremeable," is defined in his dictionary, "admitting no return.
"Autobiography, Letters and Literary Remains of Mrs. Piozzi (Thrale) (2nd ed.) (2 vols.)" by Mrs. Hester Lynch Piozzi
The sentry lulled, AEneas, blithe and brave, Seizes the pass, and leaves the irremeable wave.
"The Aeneid of Virgil" by Virgil