| Term | Definition / Meaning / Stand for |
| BLLAC |
BL Lacertae |
| BY |
BY Draconis Variable Stars |
| BICEP2 |
Background Imaging of Cosmic Extragalactic Polarization 2 |
| BIB |
Background Isotopic Behavior |
| BND |
Background Noise Density |
| BTO |
Background Thermal Offset |
| BWS |
Background Wave Signal |
| BLT |
Balloon Launch Telescope |
| BLAST |
Balloon-borne Large Aperture Submillimeter Telescope |
| BLAST |
Balloon-borne Large-Aperture Submillimeter Telescope |
| BATS |
Baltimore Astronomical Transit Survey |
| B |
Barnard catalog |
| BN |
Barnard's Nebula |
| BOSS |
Baryon Oscillation Spectroscopic Survey |
| BO |
Baryonic Oscillation |
| BLC |
Baryonic-Luminous Cosmic |
| BRA |
Baseline Reflection Analysis |
| BTE |
Baseline Transit Event |
| BCD |
Basic Calibrated Data |
| BDA |
Basic Diffraction Approximation |
| BFT |
Bayesian Factor Test |
| BES |
Beijing Electron Spectrometer |
| BATC |
Beijing-Arizona-Taiwan-Connecticut Sky Survey |
| BASS |
Berkeley Automated Supernova Search |
| BCEP |
Beta Cephei Variable Stars |
| BCVS |
Bibliographic Catalogue of Variable Stars |
| BAC |
Big Astronomy Collaboration |
| BB |
Big Bang |
| BTA |
Big Telescope Alt-azimuth |
| BSS |
Bigelow Sky Survey |
| BM |
Binary Merger |
| BNS |
Binary Neutron Star |
| BPS |
Binary Population Synthesis |
| BPC |
Binary Pulsar Core |
| BRG |
Binary Radio Galaxy |
| BSE |
Binary Star Evolution |
| BIN |
Binary System |
| BU |
Binary Unit |
| BVT |
Binary Variable Telescope |
| BWE |
Binary Wave Event |
| BWR |
Binary Wave Region |
| BWP |
Binary Waveform Profile |
| BY |
Binary Y (Binary star system in Y-formation) |
| BYF |
Binary Young Fraction |
| BZA |
Binary Zeeman Analysis |
| BZM |
Binary Zeeman Magnetism |
| BZT |
Binary Zeeman Telescope |
| BZC |
Binary Zonal Cluster |
| BZE |
Binary Zwicky Effect |
| BZG |
Binary Zwicky Galaxy |
| BZL |
Binary Zwicky Limit |
| BZP |
Binary Zwicky Pair |
| BZP |
Binary Zwicky Pattern |
| BZR |
Binary Zwicky Rotation |
| BZS |
Binary Zwicky Source |
| BZT |
Binary Zwicky Telescope |
| BZT |
Binary Zwicky Transient |
| BZV |
Binary Zwicky Variable |
| BZZ |
Binary Zwicky Zenith |
| BP |
Binding Postulate |
| BIO |
Biological Indicator Observation |
| BMD |
Biological Monitoring Device |
| BMP |
Biological Monitoring Plan |
| BBR |
Black Body Radiation |
| BB |
Black Body |
| BHC |
Black Hole Candidate |
| BHF |
Black Hole Feedback |
| BHL |
Black Hole Lensing |
| BHS |
Black Hole Spin |
| BHT |
Black Hole Theory |