OS /ˌoʊ ˈɛs/noun 4adjective 5adverb 1forms 3 noun4 •(UK) An Ordnance Survey map.We've got an OS of the Cuckmere area.Calton Hill in Edinburgh is located at OS grid ref NT262741. •Initialism of operating system.I've decided to install two different OSes on my new laptop. •Initialism of ordinary seaman. •Initialism of oppidan scholar. adjective5 •Initialism of outsize, clothes for large people. •Initialism of oversize. •Initialism of Old Style, a term used in English language historical studies to indicate that a date conforms to the Julian calendar instead of the modern Gregorian calendar. •Abbreviation of offscreen, indicating a line of dialogue is spoken by someone not visible onscreen. •Initialism of over shoulder. adverb1 •(Australia, informal) Initialism of overseas.You did the overseas trip. You went OS. — 2015 formsOS's · OSes · OSs
