Astigmatism
/əˈstɪɡ.mə.tɪ.zəm/noun
A refractive error in which the eye focuses light unevenly because the cornea or lens has an irregular curvature.
Did you know?The root behind astigmatism is Greek stigma, originally a mark or puncture made with a pointed instrument—the same ancient root behind “stigma.”
Etymological Timeline
Proto-Indo-European
PIE
*steig-
“To prick, stick, or make pointed”
Ancient Greek
Greek
stizein
“To prick or mark with a pointed instrument”
Ancient Greek
Greek
stigma
“A mark, puncture, or point”
Ancient Greek
Greek
a- + stigma
“Without a point or mark”
19th Century
English
astigmatism
“A defect of vision in which light does not focus at a single point”
Modern English
English
astigmatism
“Uneven focusing caused by irregular curvature of the eye’s cornea or lens”