The Collaborative International Dictionary of English v.0.48:

Patricide \Pat*ri"cide\, n. [L. pater father + caedere to kill.
   Cf. Parricide.]
   1. The murderer of his father.
      [1913 Webster]

   2. The crime of one who murders his father. Same as
      Parricide.
      [1913 Webster]

WordNet (r) 3.0 (2006):

patricide
    n 1: a person who murders their father
    2: the murder of your father

Moby Thesaurus II by Grady Ward, 1.0:

19 Moby Thesaurus words for "patricide":
   aborticide, fratricide, fungicide, genocide, germicide, herbicide,
   homicide, infanticide, insecticide, matricide, microbicide,
   parricide, pesticide, regicide, rodenticide, sororicide, suicide,
   uxoricide, vermicide



Bouvier's Law Dictionary, Revised 6th Ed (1856):

PATRICIDE. One guilty of killing his father.