The Collaborative International Dictionary of English v.0.48:
Camera obscura \Cam"e*ra ob*scu"ra\ [LL. camera chamber + L.
obscurus, obscura, dark.] (Opt.)
1. An apparatus in which the images of external objects,
formed by a convex lens or a concave mirror, are thrown on
a paper or other white surface placed in the focus of the
lens or mirror within a darkened chamber, or box, so that
the outlines may be traced.
2. (Photog.) An apparatus in which the image of an external
object or objects is, by means of lenses, thrown upon a
sensitized plate or surface placed at the back of an
extensible darkened box or chamber variously modified; --
commonly called simply the camera.