D defs.my
Entry 1 sense Webster, 1913

Helioscope

· He·li·o·scope · IPA
01 n. A telescope or instrument for viewing the sun without injury to the eyes, as through colored glasses, or with mirrors which reflect but a s…
  1. 1.
    A telescope or instrument for viewing the sun without injury to the eyes, as through colored glasses, or with mirrors which reflect but a small portion of light.(Astron.)