(on a firearm) a rear sight consisting of a notch across which the gunner aligns the front sight on the target.


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  • Open society

    noun a culture in which there is freedom and tolerance of belief and flexible structure, cf. closed society See closed society

  • Open software foundation

    body (OSF) A foundation created by nine computer vendors, (Apollo, DEC, Hewlett-Packard, IBM, Bull, Nixdorf, Philips, Siemens and Hitachi) to promote “Open Computing”. It is planned that common operating systems and interfaces, based on developments of Unix and the X Window System will be forthcoming for a wide range of different hardware architectures. OSF announced […]

  • Open-source

    [oh-puh n-sawrs, -sohrs] /ˈoʊ pənˈsɔrs, -ˈsoʊrs/ adjective 1. Computers. pertaining to or denoting software whose source code is available free of charge to the public to use, copy, modify, sublicense, or distribute. 2. pertaining to or denoting a product or system whose origins, formula, design, etc., are freely accessible to the public. open-source Relating to […]

  • Open source definition

    standard (OSD) Definition of distribution terms for open source software, promoted by the Open Source Initiative. ( (1999-11-28)

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