Webster's Revised Unabridged Dictionary · 1913

Adios

Adios (a`dyos") , interjection

[Sp., from Latin ad to + deus god. Compare Adieu.]

Adieu; farewell; good-by; -- chiefly used among Spanish-speaking people; as, adios amigos (good-bye friends).

This word is often pronounced ȧ*dē"os, but the Spanish accent, though weak, is on the final syllable.