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Webster 1913 Edition

(k?r-r?ˊd?-?′sh?n)

Noun.

A conjunction or concentration of rays in one point.

Bacom

Noun.

[L. See Ray.] A conjunction of rays in one point.

corradiation ‎(uncountable)

A conjunction or concentration of rays in one point.
(Can we find and add a quotation of Bacon to this entry?)