Os
| n. | 1. | A bone. |
| 1. | A mouth; an opening; an entrance. | |
| 1. | (Geol.) One of the ridges of sand or gravel found in Sweden, etc., supposed by some to be of marine origin, but probably formed by subglacial waters. The osar are similar to the kames of Scotland and the eschars of Ireland. See Eschar. | |
| 1. | (Chem.) The chemical symbol for the element osmium. |
| Noun | 1. | os - a mouth or mouthlike opening |
| 2. | Os - a hard brittle blue-gray or blue-black metallic element that is one of the platinum metals; the heaviest metal known Synonyms: atomic number 76, osmium | |
| 3. |  OS - (computer science) software that controls the execution of computer programs and may provide various servicesSynonyms: operating system | |
| 4. | OS - the left eye Synonyms: oculus sinister | |
| 5. |  os - rigid connective tissue that makes up the skeleton of vertebratesSynonyms: bone |
| 1. | OS - operating system. | ||
| 2. | OS - [obsolete, ITS], an output spy. See "OS and JEDGAR". | ||
| 3. | (operating system) | OS - An operating system from IBM for their System/360 line of hardware announced in 1964. OS was planned with several flavours that were supposed to be compatible. OS was late, memory hungry and not able to reach the marketing objectives of IBM for the 360/30, the planned successor of the IBM 1401. IBM then decided to design a new operating system for the low end machines which they called DOS/360. |