There is no single authoritative definition of "policymaker" with a specific reference citation.
In political science, a commonly cited and authoritative definition of a policymaker aligns with David Easton's concept of politics as “the authoritative allocation of values for a society.” This framework identifies policymakers as individuals or entities that play central roles in the authoritative decisions and allocations within political systems, often acting as key agents in governmental or organizational settings responsible for enacting and implementing policies.
Policymakers then are critical agent in the allocation of societal values and the governance process, framing their actions within political authority and societal needs.