D defs.my
Entry 1 sense Webster, 1913

Pelorus

· Pe·lo·rus · IPA /pɪˈlɔːɹəs/
01 n. An instrument similar to a mariner's compass, but without magnetic needles, and having two sight vanes by which bearings are taken, esp. su…
  1. 1.
    An instrument similar to a mariner's compass, but without magnetic needles, and having two sight vanes by which bearings are taken, esp. such as cannot be taken by the compass.(Navig.)