According to AZ jury instruction:
Pr-meditation means intent or knowledge to kill another human being.
"Premeditation" means that the defendant intended to kill another human being or knew [he] [she] would kill another human being, and after forming that intent or knowledge, reflected on the decision before killing. It is this reflection, regardless of the length of time in which it occurs, that distinguishes first-degree murder and second-degree murder. An act is not done with premeditation if it is the instant effect of a sudden quarrel or heat of passion. [The time needed for reflection is not necessarily prolonged, and the space of time between the intent or knowledge to kill and the act of killing may be very short.] pg PDF 71
REVISED ARIZONA JURY INSTRUCTIONS (CRIMINAL) Third Edition 2011
http://www.azbar.org/media/292098/2011_cumulative_supplement.pdf