Word Study
heliostat
CIDE DICTIONARY
heliostat, n. [Helio- + Gr. placed, standing, fr. to place, stand: cf. F. héliostate.].
An instrument consisting of a mirror moved by clockwork, by which a sunbeam is made apparently stationary, by being steadily directed to one spot during the whole of its diurnal period; also, a geodetic heliotrope. [1913 Webster]
OXFORD DICTIONARY
heliostat, n. an apparatus with a mirror driven by clockwork to reflect sunlight in a fixed direction.
Derivative
heliostatic adj.
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