noun \ō-ˈpas-ət-ē\
plural opac·i·ties

Definition of OPACITY

: the quality or state of a body that makes it impervious to the rays of light; broadly : the relative capacity of matter to obstruct by absorption or reflection the transmission of radiant energy (as X-rays, infrared radiation, or sound)
: an opaque spot in a normally transparent structure (as the lens of the eye)

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