The Collaborative International Dictionary of English v.0.48:

Alguazil \Al`gua*zil"\, n. [Sp. alguacil, fr. Ar. alwaz[imac]r
   the vizier. Cf. Vizier.]
   An inferior officer of justice in Spain; a warrant officer; a
   constable. --Prescott.
   [1913 Webster]