D defs.my
Entry 1 sense Webster, 1913

Theodolite

· The·od·o·lite · IPA /θiːˈɒdəlaɪt/
01 n. An instrument used, especially in trigonometrical surveying, for the accurate measurement of horizontal angles, and also usually of vertica…
  1. 1.
    An instrument used, especially in trigonometrical surveying, for the accurate measurement of horizontal angles, and also usually of vertical angles. It is variously constructed.