Douglas Harper's Etymology Dictionary
1807, from prefecture + -al (1).
Wiktionary
a. Of, pertaining to or at the level of a prefecture
WordNet
adj. of or relating to a prefecture; "a prefectural museum"
Usage examples of "prefectural".
The great audience chamber of the Prefectural Palace was literally packed with people.
Before becoming a monk, he had distinguished himself as a licentiate in the Chuzhou prefectural school.
At each prefectural or county town he came to, he stayed several months.
It was one afternoon during the spring, about a year after the end of the war, while I was on my way back from picking up medicine for little Juntaro at the Kamigyo Prefectural Hospital.
During the final two years before Gion closed, there was a man named Sato who used to go to parties as a guest of the Prefectural Governor.