† dioptraladj.
Obsolete.
= dioptric adj.
ΘΚΠ
the world > physical sensation > sight and vision > optical instruments > instruments to refract, etc., light > [adjective] > refractor
dioptral1610
dioptric1653
dioptic1656
dioptrical1664
refracting1747
dioptical1818
1610 W. Folkingham Feudigraphia ii. ii. 50 Degrees of angular production obserued by some Dioptrall instrument.
This entry has not yet been fully updated (first published 1896; most recently modified version published online June 2019).
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adj.1610