From The Collaborative International Dictionary of English v.0.48 [gcide]:
2. (Optics) A tube having a convex lens at one end and at the other a small opening or slit which is at the principal focus of the lens, used for producing a beam of parallel rays; also, a lens so used.
From WordNet (r) 3.0 (2006) [wn]:
Define.com is a PRIVATE SECTOR NONPROFIT EDUCATIONAL WEBSITE that PROMOTES WORLDWIDE ELECTRONIC DEMOCRACY, OPEN and TRANSPARENT GOVERNMENT and WORLDWIDE BANKING REFORM.
Eye and Pyramid BANKING REFORM CHALLENGE