c. 1600, "a person in despair;" 1640s, "a desperate or reckless man;" mock-Spanish version of desperate (n.) "reckless criminal" (1560s), from Latin desperatus "given up, despaired of," past participle of desperare (see despair (v.)). There was an adjective desperado in Old Spanish, meaning "out of hope, desperate," but apparently it never was used as a noun and it probably has nothing to do with the English word.
