| A-X | Attack, Experimental 
| Others |
| A. | Atlantic Reporter
| Others |
| A. C. MOORE ARTS | Arts & Crafts Moore (more)
| Others |
| A. K. Khandker | Abdul Karim Khandker
| Others |
| A.2D | Atlantic Reporter, 2nd Series
| Others |
| A.A | Amino Acids
| Others |
| a.a. | of each (from Latin ana ana)
| Others |
| A.B. | Artium Baccalaureaus
| Others |
| A.C. | after food (ante cibum) [Lat.]
| Others |
| A.C. | Ante Cibum (before meals)
| Others |
| a.c. | before a meal (Latin ante cibum)
| Others |
| A.D | Analogue to Digital
| Others |
| A.D. | Christian era (anno Domini [Lat.])
| Others |
| a.d. | right ear (Latin auris dexter)
| Others |
| A.D. /B.C. | Macintosh Assembly Source Code
| Others |
| A.F. | Amniotic Fluid
| Others |
| A.F.& A.M. | Ancient Free and Accepted Masons
| Others |
| A.G.E | Agape Generation of Eagles
| Others |
| A.I. | Ad Interim (in the meantime)
| Others |
| A.L.R.2D | American Law Reports, 2nd Series
| Others |
| A.L.R.3D | American Law Reports, 3rd Series
| Others |
| A.L.R.4TH | American Law Reports, 4th Series
| Others |
| A.L.R.5th | American Law Reports, 5th Series
| Others |
| A.L.R.6th | American Law Reports, 6th Series
| Others |
| A.L.R.FED. | American Law Reports, Federal
| Others |
| A.M | Alternative Medicine
| Others |
| A.M. | Ante Meridiem (take before noon)
| Others |
| a.m. | ante meridiem - morning, before noon
| Others |
| A.M. | Member of the Order of Australia
| Others |
| A.Mus.A. | Associate in Music, Australia
| Others |
| A.N.D | A Natural Death
| Others |
| a.p. | before a meal (Latin ante prandium
| Others |
| A.P.P. | Additional Public Prosecutor
| Others |
| A.T.C.L | Associate of Trinity College London
| Others |
| A.T.S. | Anti-Tetanus Serum
| Others |
| A/A | Air to Air
| Others |
| A/A | AttAching
| Others |
| A/A/O | Anaerobic/Anoxic/Oxic
| Others |
| A/B | Acid/Base ratio
| Others |
| A/C | Acceptance Criteria
| Others |
| A/C | Account Current
| Others |
| A/C | Air Conditions
| Others |
| A/C | Aircraft
| Others |
| A/C | Albumin/Creatinine ratio
| Others |
| A/C | Anterior Chamber of eye
| Others |
| A/C | Associate Contractor
| Others |
| A/CH | Alternate CHannel
| Others |
| A/CNK | Al2O3/(CaO + Na2O + K2O) (Shands Index)
| Others |
| A/D | Active Duty
| Others |
| A/D | AeroDrome
| Others |