| BAC | Bacterial Artificial Chromosome | In English | → Genetics → Biochemistry, biophysics |
| BAC | Boeing Aerospace Company | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| BAC | Boeing Aircraft Company | In English | → Aeronautics, aircraft |
| BAC | Booster Assembly Contractor | In English | → Spaceflight engineering, astronautics |
| BAC | Budget At Completion | In English | |
| BAC | Buffer Access Card | In English | |
| BAC | Basic Access Control | In English | |
| BAC | Béton Armé Continu | In French | → Civil engineering → Civil engineering and land transport → Building |
| BAC | Bio Affinity Company | In English | → Biotechnology |