OOO, Ooo, or ooo may refer to: Frequently used abbreviations OoO, an abbreviation for Out of Office, a phrase often used in professional contexts to indicate that someone is unavailable for work (usually because they are on vacation) ООО, a type of private limited company () in Russia Arts, entertainment, and media Kamen Rider OOO, a 2010–11 tokusatsu series Kamen Rider OOO (character), a fictional character from the tokusatsu series of the same name The Land of Ooo, the setting of Adventure Time OOO, the production code for the 1972 Doctor Who serial The Time Monster "Ooo", a song by !!! from their 2015 album As If "Ooo", a track from the soundtrack of the 2015 video game Undertale by Toby Fox O.O.O (Over&Over&Over), theme song of Girls Planet 999 and Kep1er version, recorded in First Impact Computing and networking .OOO, an Internet top-level domain OpenOffice.org, a discontinued office application suite Out-of-order execution, a paradigm in microprocessors Other uses OOO gauge, an old British model railway scale Order of operations, in evaluating mathematical expressions Object-oriented ontology, a metaphysical school of thought O-O-O, long (or queenside), castling in chess See also Triple-O (disambiguation) 000 (disambiguation) (three zeros) O00, the Alturas Municipal Airport One on One (disambiguation) Out of Order (disambiguation) Three Rings Design, an online game developer OO (disambiguation)