1MC — 1 Main Circuit, the shipboard public address circuit.
Aft — toward the back of a vessel, opposite of fore or forward.
AI — Artificial Intelligence, a synthetic, inorganic consciousness capable of knowledge retention, learning, and reasoning at capacities and speeds far exceeding those of the human mind.
AR — Assault Rifle, a fully automatic bullpup rifle, and the workhorse of the United Nations Space Command.
ASAP — As Soon As Possible.
BIOCOM — a Freelancer armor enhancement that allows soldiers to check the vitals of teammates.
BR — Battle Rifle, or BR85, a select-fire rifle capable of firing three-round bursts and fully automatic fire.
C-12* — Composition 12, a malleable plastic explosive.
CMT* — Chorus Mean Time, the local time at the Mazurka Observatory in Armonia, Chorus, used to coordinate planetwide operations.
Destroyer — a class of UNSC warship designed with the speed and maneuverability required to escort and defend larger vessels. The Halberd class is distinguished by its arrowhead nose and reinforced hull.
DMR — Designated Marksman Rifle, or M392, a gas-operated select-fire bullpup rifle considered to be the "big brother" of the battle rifle.
Exfil — Exfiltration, or extraction, the process of removing military personnel from a hostile environment.
FAC — The Federal Army of Chorus.
Fed — shorthand for a former member of the FAC.
F.I.L.S.S. — Freelancer Integrated Logistics and Security System, an artificial intelligence from Project Freelancer, recovered after the project's downfall by Charon personnel.
HUD — Heads-Up Display, a transparent display that projects data directly onto the user's visor.
IFF — Identification Friend or Foe, an encoded signal automatically transmitted on a specific frequency used to delineate teammates from hostiles.
IV — Intravenous therapy, a mean of administering fluids, medications and nutrients, directly into a person's vein.
Keel — the fore-aft structure at the bottom of a vessel's hull.
Knee-knockers — an opening in a bulkhead through which personnel may pass. The lower lip of the opening sits at shin-height.
LT — Lieutenant, often pronounced "el-tee".
M6 — or "magnum", a semiautomatic, magazine-fed pistol or sidearm known for its ruggedness and power.
M870 — 50mm coilguns used on UNSC warships for the purposes of point-defense, usually controlled by the ship's artificial intelligence.
MAC — Magnetic Accelerator Canon, a large coilgun used on UNSC warships that accelerate large metallic slugs to supersonic speeds.
Needler — the T-33 GML, an alien, fully-automatic pistol famous for its pink needle-shaped projectiles.
New — shorthand for a former member of the New Republic.
Pelican — the D77H-TCI, a multirole dropship capable of ferrying 14 personnel, light vehicles, and/or heavy armament intra- and extra-atmosphere.
Port — the left-hand side of a vessel, or pertaining to the left-hand side of a vessel.
SA — Situational Awareness, a decision making element consisting of the complete understanding of a dynamic task environment how it could change.
SP — Security Patrol, a group of soldiers tasked with patrolling and securing a specific area or location.
Starboard — the right-hand side of a vessel, or pertaining to the right-hand side of a vessel.
TEAMCOM — a communications channel that provides audio and data linkage between members of a particular team.
UAC — United Army of Chorus, the force resulting in the integration of the Federal Army of Chorus and the New Republic.
UNSC — United Nations Space Command, the military, exploratory, and scientific agency of the Unified Earth Government.
*Indicates the author has exercised artistic license, i.e. the term is not established in present-day, Halo, or Red vs. Blue lexicon.