1610, "a person in despair," mock-Spanish version of desperate (n.) "reckless criminal" (1563), from L. desperatus (see desperation). There was an adj. desperado in O.Sp., meaning "out of hope, desperate," but apparently it never was used as a noun and it probably has
nothing to do with the Eng. word. Meaning "a desperate or reckless man" is recorded from 1647.