ODN - (Optical Data Network) a system of fiber optic cables on board starships and space stations that is used for data transfer between computers and remote terminals.
Odo - A Changeling who served as Chief Security Officer on Deep Space 9.
offer of Appreciation - A reward in Star Trek Online for doing an Aid the Planet mission. By right-clicking on it and choosing "Use" you can open it to get an item.
Omarion Nebula - An interstellar gas cloud located in the Gamma Quadrant, deep inside Dominion space which had the Founder's homeworld.
omega - The last letter in the Greek alphabet. Also used to denote the end of something,
Omega directive - A general directive of all Starfleet captains ordering them to contact Starfleet when an Omega molecule is detected.
omega force - A fleet made up of Federation, Klingon, and Romulan ships. It is represented as a reputation system in Star Trek Online.
oomox - The act of massaging a Ferengi's ears.
OP - 1) Original Poster; 2) Original Post; 3) Over powered
ops - Operations
orbit - The circular path of an object around a star, planet, or moon.
organic - Relating to living matter
organism - An individual animal, plant, or single-celled life form
OS - Orbital Strike (Engineering Ability)
Ow - Overwatch (Tactical Ability)
owned - In video game terms, it is when someone defeats another player or something in the game.