| Term | Definition / Meaning / Stand for |
| AAVSO |
American Association of Variable Star Observers. |
| ADAF |
Advection Dominated Accretion Flow, a mechanism by which matter is slowly accreted onto a black hole. |
| AGB |
Asymptotic Giant Branch, a type of red giant star. |
| ANGST |
ACS Nearby Galaxy Survey Treasury |
| ANS |
Astronomical Netherlands Satellite. |
| ASCOT |
Astronomical Comet Observatory Team |
| ASSA |
Astronomical Society of Southern Africa |
| AST |
Advanced Space Telescope |
| ASTRO |
Astronomy Space Telescope Research Observatory |
| ATST |
Advanced Technology Solar Telescope |
| AU |
Astronomical Unit, the average distance between Earth and the Sun. |
| AU |
Astronomical Unit |
| AVN |
African VLBI Network |
| AZT |
Altazimuth Telescope |
| BAO |
Baryon Acoustic Oscillations |
| BAS |
British Antarctic Survey |
| BB |
Black Body. |
| BC |
Blackbody Curve |
| BEM |
Blackbody Emission Model |
| BEM |
Boundary Element Method (used in simulations) |
| BGO |
Bismuth Germanium Oxide (detector material) |
| BHT |
Black Hole Thermodynamics |
| BICEP2 |
Background Imaging of Cosmic Extragalactic Polarization 2, a cosmic microwave background experiment. |
| BM |
Brane Model (cosmology) |
| BOL |
Beginning of Life (term used in cosmology) |
| BOSS |
Baryon Oscillation Spectroscopic Survey |
| BP |
Brightest Point (of a light curve) |
| BV |
Blue-Violet (color index in stars) |
| C |
First Cambridge Catalogue of Radio Sources |
| CASCA |
Canadian Astronomical Society / Societe canadienne d'astronomie |
| CASS |
Center for Astrophysics & Space Sciences |
| CCS |
Cool Carbon Star |
| CDS |
Centre de Donnees astronomiques de Strasbourg |
| CEGP |
Close-in Extrasolar Giant Planet |
| CEPS |
Center for Earth and Planetary Studies |
| CFS |
Cosmic Fluid Structure |
| CHeB |
Core Helium Burning |
| CIR |
Corotating Interaction Region (solar wind phenomenon) |
| CMA |
Coronal Mass Analysis |
| CMB |
Cosmic Microwave Background |
| COAST |
Cambridge Optical Aperture Synthesis Telescope |
| COMSAT |
Communications Satellite |
| CPE |
Cosmic Plasma Environment |
| CR |
Cosmic Rays |
| CRISM |
Compact Reconnaissance Imaging Spectrometer for Mars |
| CRRES |
Combined Release and Radiation Effects Satellite |
| CRS |
Cosmic Ray Spectrometer |
| CSA |
Cryogenic Sample Analysis |
| CSM |
Command and Service Module (Apollo Program) |
| CSP |
Commercial Spaceflight Program |
| Clementine |
Lunar Mapping Mission |
| DAI |
Data Acquisition Interface |
| DAMPE |
Dark Matter Particle Explorer |
| DANDE |
Drag and Atmospheric Neutral Density Explorer |
| DAP |
Diffuse Astrophysical Plasma |
| DASCH |
Digital Access to a Sky Century at Harvard |
| DASI |
Degree Angular Scale Interferometer |
| DC |
White Dwarf, No Significant Spectral Lines |
| DEEP |
Deep Extragalactic Evolutionary Probe |
| DES |
Dark Energy Survey |
| DF |
Dark Matter Free (Galaxy Type) |
| DIBRE |
Diffuse Infrared Background Experiment |
| DLE |
Dust Line Emission |
| DLT |
Diffraction Limited Telescope |
| DMF |
Dark Matter Fraction |
| DMS |
Dark Matter Survey |
| DNR |
Deep Near-Infrared (Astronomy) |
| DNS |
Double Neutron Star |
| DPC |
Data Processing Center |
| DPS |
Double Pulsar System |