/O-S/ , noun, invariant 1. (Architecture) Ateliers O-S architectes Architecture and town planning firm, located in Paris since 2002. 2. (Chemistry) symbol of chemical element osmium. 3. (Anatomy) From latin os. The hard dense tissue that forms the skeleton of vertebrates, providing structural support for the body and serving as an attachment for muscles. 4. (Computing) Open-source. Applied to computer software that is available in source code form for which the source code and certain other rights normally reserved for copyright holders are provided under a software license that permits users to study, change, and improve the software. 5. (Computing) Acronym of Operating System. Software on a computer that manages the way different programs use its hardware, and regulates the ways that a user controls the computer. 6. (Familiar) (French) Problem, obstacle or unexpected situation. 7. (Slang) (Familiar) Suffix generating adverb, for distorting purpose. speed - speedos.8. (Building) (French) Acronym of Ouvrier Spécialisé (semi-skilled worker). Someone who does a specific work that doesn't need professional qualifications.9. (Agreement) (French) An Ordre de Service (OS) is a certificate that notify a decision to the holder of the contract, according to the conditions specified in the contract. 10. (Military) Third grade sailor.