inspector (n.)

c. 1600, "overseer, superintendent," from Latin inspector "one who views or observes," agent noun from past participle stem of inspicere "look at, observe, view; look into, inspect, examine," from in- "into" (from PIE root *en "in") + specere "to look" (from PIE root *spek- "to observe"). As a police ranking between sergeant and superintendent, it dates from 1840. Related: Inspectorial (1752). Of the 18c. feminine formations, inspectrix (1703) is earlier than inspectress (1737).