D defs.my
Entry 2 senses Webster, 1913

Detector

/dĭt-ĕk'-tẽr/ · De·tect·or · IPA /dɪˈtɛktə(ɹ)/
01 n. One who, or that which, detects; a detecter.
  1. 1.
    One who, or that which, detects; a detecter.
    “A deathbed's detector of the heart.” Young.
  2. 2.
    An indicator showing the depth of the water in a boiler.(Elec.)
Phrases & compounds
Bank-note detector — a publication containing a description of genuine and counterfeit bank notes, designed to enable persons to discriminate between them.
Detector lock — See under Lock.