c. 1600, "a person in despair," mock-Spanish version of desperate (n.) "reckless criminal" (1560s), from Latin desperatus (see desperation). 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. Meaning "a desperate or reckless man" is recorded from 1640s.
