| Atlas Shrugged | Atomic number | Atlantic Ocean |
| Atlas | Attila the Hun | Atheism |
| AtomFor alternative meanings see atom (disambiguation). An atom is a microscopic structure found in all ordinary matter around us. Atoms are composed of 3 types of subatomic particles: electrons, which have a negative charge; protons, which have a positive ch | AtaxiaAtaxia is unsteady and clumsy motion of the limbs or trunk due to a failure of the fine coordination of muscle movements. The cerebellum is the center of the fine coordination of muscle movements, while the information emerging from it is carried to the m | Atlantic (disambiguation)The Atlantic is a major ocean in the world; see Atlantic Ocean and transatlantic. Atlantic is the name of a place in Canada Atlantic, Nova Scotia Atlantic is the name of some places in the United States of America: Atlantic, Iowa Atlantic, Pennsylvania At |
| AthenaThis article is about the goddess Athena. For other uses see Athena (disambiguation). Aegina Athena ( Phoenician Onga also transliterated as Athene the Greek goddess of wisdom, strategy, and war associated by the Romans with their Etruscan goddess Minerva | AtomicThe general meaning of "atomic" is "irreducible". That is, reduced to the smallest possible part. It has more specific meanings in several contexts: In chemistry, chemical atoms are grouped by type in the periodic table and consist of particles as describ | Atomic physicsAtomic physics (or atom physics is physics of the electron hull of atoms. Lay people often associate the term atomic physics with nuclear power and nuclear bombs, obviously due to the synonymous use of atomic and nuclear in standard English. However, phys |
| Atomic orbitalAn atomic orbital is the mode of behavior of an electron in an atom (see first Electron orbital). A given orbital is identified by unique values of three quantum numbers: , , and. The various types of orbitals An orbital is uniquely identified by the valu | AthensAcropolis in central Athens is home to ancient monuments of Athens — a mainstay of its thriving tourism industry Athens ( Greek: Athina is the capital of Greece, and also the capital of the Attica region of Greece. A cosmopolitan modern city, Athens is al | Atanasoff Berry ComputerAtanasoff Berry Computer is the name applied, long after the fact, to an experimental machine for solving systems of simultaneous linear equations, developed in 1938-42 at Iowa State University by Dr. John Vincent Atanasoff and Clifford E. The Atanasoff-B |
| Athenian democracy | ATP (disambiguation) | Atmosphere |
| Attorney | Atomic semantics | Atle Selberg |
| Atlantic Baptist University | AT&T | Atlanta Falcons |
| Atlanta Braves | Atari ST | Atlantis |
| Atari | Atomic clock | Atlantic Avenue Tunnel |
| Athanasian Creed | ATM | Atlas Computer (Manchester) |
| Atomic absorption spectroscopy | Atlas Autocode | Atari 2600 |
| Atari 5200 | Atari 7800 | Atari Jaguar |
| Atari Lynx | Atacama | Atomic theory |
| Athlon | Atlanta, Georgia | Attribution of recent climate change |
| Atom probe | Athanasius of Alexandria | Atomic weight |
| At bat | Atalanta | ATTAC |
| Atomic mass | ATF | Atmospheric duct |
| Attack time | Attenuation | Attenuation constant |
| Attenuator | Attribute | Atlantic cod |
| Atomic mass unit | AT | Athletics |
| ATRAC | Atmospheric reentry | Atonality |
| Atbash | Atlas (moon) | Atlas (mythology) |
| Atlas (cartography) | Atlas (anatomy) | Atlas mountains |
| Atlas (architecture) | Atlas (topology) | Aten |
| Atmospheric pressure | Atoll | Atil |
| Atari demos | Atomic, molecular, and optical physics | Atomic radius |
| Atlantic slave trade | Attic | Attorney General |
| Atomic nucleus | ATA | Attica (disambiguation) |
| Athelstan of England | Atlantic Records | Attack on Pearl Harbor |
| ATLAS | Atari 8-bit family | Atlantic League |
| Athelas | Attention-deficit hyperactivity disorder | Atlantic City Surf |
| Athletics at the 1896 Summer Olympics | Attention | Athens, Ohio |
| Atlanta Thrashers | Atlantic Canada | Atacama Region of Chile |
| Atlanta Hawks | Athanaric | Athyriales |
| Attila (disambiguation) | Athamas | Atlantic Coast Conference |
| Atomium | Attitude control | Athos |
| Ate | Atlantic Ten Conference | Athalaric |
| Atreus | Athletic Bilbao | Atikamekw |
| Atreidae | Atkins Nutritional Approach | Atlético de Madrid |