ōˈpasəd.ē, -sətē, -i noun
( -es )
Etymology: French opacité, from Latin opacitat-, opacitas, from opacus shaded, dark + -itat-, -itas -ity
1. : the quality or state of an instance of being shaded or obscure : darkness , obscurity
2.
a. : the quality or state of a body that renders it impervious to the rays of light : lack of transparency or translucency
b. : degree of nontransparency
titanium dioxide has the greatest opacity and tinctorial strength of all white pigments — Andries Voet
c. : the property of a photographic image that causes partial absorption of rays of light
d. : the capacity of matter to obstruct by absorption or reflection the transmission of forms of radiant energy in addition to light (as radio waves, infrared radiation, sound)
the opacity to ultrasound of porous media — A.B.Wood
also : a measure of this capacity : the reciprocal of the transmissivity
3.
a. : obscurity of sense : lack of clearness : unintelligibleness
b. : mental dimness or obtuseness : dullness
4. : an opaque spot on a normally transparent structure (as the cornea or lens of the eye)