Word Study
halation
CIDE DICTIONARY
halation, n.
An appearance as of a halo of light, surrounding the edges of dark objects in a photographic picture. [1913 Webster]
OXFORD DICTIONARY
halation, n. Photog. the spreading of light beyond its proper extent in a developed image, caused by internal reflection in the support of the emulsion.
Etymology
irreg. f. HALO + -ATION
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