Final answer:
TACON (Tactical Control) is the term that best describes who has temporary tactical authority over the unit assigned to him or located in his area.
Step-by-step explanation:
The term that best describes who has temporary tactical authority over the unit assigned to him or located in his area is TACON (Tactical Control).
TACON refers to the authority granted to a commander to direct forces within the boundaries of his operational area or the limits of the unit assigned to him.
It is important to note that TACON authority is temporary and is specifically defined by the higher-level command.