Source : Webster's Revised Unabridged Dictionary (1913)

Premeditation \Pre*med`i*ta"tion\, n. [L. praemeditatio: cf. F.
   pr['e]m['e]ditation.]
   The act of meditating or contriving beforehand; previous
   deliberation; forethought.

Source : WordNet®

premeditation
     n 1: planning or plotting in advance of acting [syn: {forethought}]
     2: (law) thought and intention to commit a crime well in
        advance of the crime; goes to show criminal intent