D defs.my
Entry 1 sense Webster, 1913

Astigmatism

/əs-tĭg'-mət-ĭzˌ-əm/ · A·stig·ma·tism · IPA /əˈstɪɡmətɪzm̩/
01 n. A defect of the eye or of a lens, in consequence of which the rays derived from one point are not brought to a single focal point, thus cau…
  1. 1.
    A defect of the eye or of a lens, in consequence of which the rays derived from one point are not brought to a single focal point, thus causing imperfect images or indistinctness of vision.(Med. & Opt.)