ashore - When a ship's crew leaves the vessel, they are "ashore". Though normally used regarding planets, it can refer to boarding a space station.
aweigh - When a ship releases the equipment tethering it to a space station or surface dock, it is "aweigh".
aye, aye - The proper way to acknowledge an order. If told to attack the correct response is "Aye, aye, sir." If asked "Are you proud to be a marine?" the correct response is "Yes, sir."
ASAP - Pronounced "a-sap", an acronym of "as soon as possible".
belay - Stop, cease.
bridge - The navigation center of a spacecraft, where the steering is done.
captain's mast - Non-judicial disciplinary proceedings by unit commanders.
CIC - Combat Information Center, the command center of a spacecraft. The CIC is filled with sensor displays to make sense out of the chaos of combat.
DC - Damage Control. The containment and repair of damage to a spacecraft.
ECM - Electronic Counter-Measures used to avoid enemy sensors, from passive emissions masking to active jamming.
EVA - Extra-Vehicular Activity. Time spent in a pressure suit, outside of a vehicle, spacecraft, or station.
flank - The flank is the "side" of a military formation. Since the soldiers are facing elsewhere, an enemy that can attack on the flank can often "turn it" or "roll it up".
FNG - "Freaking" New Guy(s). A derisive term for inexperienced personnel.
groundside - The surface of a planet.
helmsman - The crewmember who pilots the spacecraft.
ladar - Light-amplified detection and ranging. An active sensor that bounces lasers off an object to determine its bearing and distance. Ladar has sufficient resolution that the data can be reconstructed into an image.
shore party - Spacecraft's crew sent ashore on official business.
silent running - An old submariner's term used aboard the Normandy to denote when stealth systems are active.
sitrep - Abbreviation of "situation report", an evaluation of the current military situation.
spacer - Someone who has spent most of their life in space.
XO - Executive Officer, the second-in-command of an Alliance warship. The XO is responsible for administrative and personnel matters.