A5	Atlas V rocket built by ULA
ACES	Advanced Cryogenic Evolved Stage, the ULA new Upper Stage for Vulcan rocket
AE	Ascent Element (HLS terminology)
ANSMET	Antarctic Search for Meteorites (NSF funded program in USA)
ARES	Astromaterials Research and Exploration Science Division at NASA JSC
ATV	All-Terrain Vehicle (FLARE terminology) or Automated Transfer Vehicle (basis of ESM)
CC	Crew Capsule (HLS terminology)
CFM	Cryogenic Fluid Management (HLS terminology)
CIII	Centaur III upper-stage built by ULA for Atlas V rocket
CLV	Commercial Launch Vehicle delivering payload to LEO or TLI (HLS terminology)
CM	Apollo Command Module
COPV	Composite Overwrap Pressure Vessels, component of the FLARE AE
CV	Centaur V upper-stage built by ULA for Vulcan rocket
DAC	Design Assessment Cycle, NASA evaluation of architectures for Artemis program
DAE	Fused (single-stage) Descent-Ascent Element, Combined (HLS terminology)
DE	Descent Element (HLS terminology)
DoD	Department of Defense
ECPO	Elliptical Coplanar Posigrade Orbit, a possible orbit being studied by HLS for Artemis
EML1	Earth-Moon L1 point
EML2	Earth-Moon L2 point
EOR	Earth Orbit Rendezvous, a concept considered for Apollo stages before TLI
ESA	European Space Agency
ESM	European Service Module (based on Automated Transfer Vehicle, ATV)
F9	Falcon 9 built by SpaceX
FH	Falcon Heavy built by SpaceX
FLARE	Flexible Lunar Architecture for Exploration, an alternate architecture scenario for NASA's Artemis Program
HALO	Habitation and Logistics Outpost (former "Mini-Hab" Gateway component before 2019)
HEO	High Earth Orbit
HLS	Human Landing System (HLS) - NASA team developing the Artemis human lander
ICPS	Interim Cryogenic Propulsion Stage (ICPS), upper-stage for the NASA SLS Block 1
ISS	International Space Station, NASA vehicle located in Earth's LLO at 51.6° inclination
LLFPO	Low Lunar Frozen Polar Orbit, a specific LLO at 86.5° inclination
LBM	Lunar Braking Module, a concept not adopted by Apollo using EOR
LEM	Lunar Excursion Module (LEM), later Lunar Module (LM) from the NASA Apollo program
LEO	Low Earth Orbit, for FLARE defined as a 28.5° inclination, 400 km circular Earth orbit
LES	Orion Launch and Entry Suit
LLO	Low Lunar Orbit, for FLARE a 100 km circular orbit above the lunar surface
LOI	Low Orbit Insertion burn to place a vehicle in orbit around the Moon
LORAD	Lunar Operations with Reuse and Assisted Descent (HLS terminology)
LATV	Lunar All-Terrain Vehicle (FLARE terminology) for a 1-person, 3-wheel electric vehicle
LTV	Lunar Terrain Vehicle, 4-wheel, 2-person “buggy” style lunar rover
MH	Minihab module (derived from the Cygnus vehicle) component of the Gateway vehicle
MMH	Mono-Methyl Hydrazine, CH3(NH)NH2, storable rocket propellant
MMOD	Micro-Meteoroid and Orbital Debris
MPCV	Multi-Purpose Crew Vehicle, another name for NASA's Orion capsule
MPS	Main Propulsion System (HLS terminology)
NextSTEP	Next Space Technologies for Exploration Partnerships: NASA public-private partnership
NRHO	Near Rectilinear Halo Orbit (rp = 3300 km, ra = 65,000 km in HLS terminology)
NSF	National Science Foundation
OCSS	Orion Crew Survival System (OCSS), orange colored ascent/entry suits for NASA crew
OME	Orbital Maneuvering Engine, part of the ESM and lunar lander AE
PF	Performance Fraction, a method to estimate delivery of mass to certain ΔV targets
PIR	Persistently Illuminated Regions of the Moon (near the poles)
PMF	Propellant Mass Fraction (HLS terminology)
PPE	Power and Propulsion Element, component of the Gateway vehicle
PSR	Permanently Shadowed Region on the Moon (near poles)
RCS	Reaction Control System
RF	Radio Frequency
RFID	Radio Frequency Identification
RMS	Remote Manipulator System, a mechanical arm for spacecraft to move external objects
RPOD	Rendezvous, Proximity Operations and Docking phases of mating vehicles in orbit
RST	Return SpaceTug (FLARE terminology), vehicle pushing Orion + ESM to Earth from Moon
SLS	Space Launch System, a proposed family of rockets being developed by NASA
SLS B1	SLS Block 1 rocket, which delivers up to 26 mt to TLI (HLS terminology)
SM	Apollo Service Module
TA	Tug Adaptor (FLARE terminology), equipment to convert a Centaur US into a SpaceTug
TCM	Trajectory Correction Maneuver
TE	Transfer Element (HLS terminology)
TE1	TE for AE/DAE for orbit to orbit transfer or initial braking (HLS terminology)
TE2	TE for TE1 and provides orbit to orbit transfer and/or initial deorbit (HLS terminology)
TEI	Trans-Earth Injection burn to send a vehicle into the Earth's gravity field
TLI	Trans-Lunar Injection burn to send a vehicle into the Moon's gravity field
TRL	Technology Readiness Level
ULA	United Launch Alliance, rocket company formed in 2006
USA	United States of America
xEMU	Exploration Extravehicular Mobility Unit, NASA space suit for lunar surface exploration
ZBO	Zero Boil-Off, concepts to limit the loss of cryogenic LOX/LH2 in spacecraft