noun
head patrol officer; senior patrol officer
A rank in the Japanese police force, above 巡査 (patrol officer) and below 巡査部長 (police sergeant).
彼は巡査長に昇進した。
He was promoted to head patrol officer.
巡査長は交番で勤務している。
The senior patrol officer is working at the police box.
巡査部長 is the next rank above 巡査長, equivalent to police sergeant.
Compound of 巡査 (patrol officer) and 長 (chief, head). The exact historical derivation is uncertain, but the term follows a common pattern for naming ranks in Japanese organizations.