Things That Start With A

According to the World of Science dictionary, over 100 science-related terms start with the letter A, from abiotic to atomic to azygos. This article catalogs a number of scientific words and concepts that begin with the letter A; concepts that help build a general backbone of scientific knowledge.

With that in mind, grad you dictionaries as we look at some important things that begin with the letter A.

Scientific Terms/Concepts That Begin With The Letter A


Acceleration refers to the change in velocity of a body over time. Acceleration is an extremely important concept in physics, and most of modern kinematics owes its existence to the precise mathematical formulation of the concept of acceleration. The equation for average acceleration is: (Vf−Vi)/T=A, where Vf stands for final velocity, Vi stands for initial velocity, and T stands for time.


Probably one of the more recognizable scientific terms, the word “atom” refers to the smallest unit of a chemical element. Atoms are composed out of 3 kinds of particles, protons, neutrons, and electrons. Protons and neutrons are gathered together in the nucleus of the atom and the electrons exist in an exterior shell. Common illustrations depict the electrons of an atom orbiting the nucleus like planets in a solar system, but this representation is fundamentally inadequate and is simply a useful visualization tool. Protons and neutrons are, in turn, composed of smaller particles known as quarks.


An acid is a chemical compound that is capable of donating a hydrogen atom to form an acidic aqueous solution, Acids form aqueous solutions that are generally sour in taste, react readily with bases and certain metals to form salts, turn litmus paper blue, and can damage human skin if come into contact with concentrated amounts. Common acids include hydrochloric acid found in the human gastrointestinal tract, sulfuric acid used in car batteries, citric acid found in many fruits, and acetic acid used for modern electronics and printing.

Alpha Centauri

Alpha Centauri has the distinction of being the solar system closest to our own. Alpha Centauri is a solar system about 3.47 light-years away and consist of 3 stars, Alpha Centauri A, B, and C. A and B form a binary pair of stars that orbit around each other and Alpha Centauri, sometimes Proxima Centauri, has the distinction of being the closest known star to our own at a distance of 4.24 light years.


The term archaea refers to a domain in the phylogenetic tree of life that consists mostly of single-celled prokaryotic organisms. Archae are distinguished from the other major domain of prokaryotic organisms Bacteria, in that Archeae have a unique cell wall composition and mechanisms of gene expression that are more closely related to those of multicellular eukaryotes. Many archaea are noted for being capable of surviving in extreme environments, such as in the intense heat of ocean floor vents or the acidic conditions of salt lakes. Archaea represent a relatively new clade of biological organization, first being named in 1977 as an alternative to schemas that classified all prokaryotic organisms together in the same group.


An allele is a variant form of a given gene. The presence or absence of different alleles can manifest as phenotypic differences, such as different color or shape. The concept of the allele was first introduced by the Augustinian friar and botanist Gregor Mendel, whose groundbreaking experiments cross-breeding pea plants laid the foundation for the classical study of genetics and hereditary. His mathematical laws that describe the combination and distribution of alleles in a given population are now referred to as the laws of Mendelian inheritance.


Adenosine Triphosphate (ATP) is a complex organic molecule that serves are the primary energy currency of living organisms. Any physiological process requiring energy has that energy delivered to it in the form of ATP. ATP is an energy dense molecule and has a number of high energy bonds, so it is an ideal substrate for the transfer of energy through the body.


You probably hated it in high school, but did you know that the word Algebra comes from the Arabic word “al-jabr,” which literally means “the reunion of broken parts”? Algebra as a branch of mathematics is so named because it is primarily concerned with the manipulation of mathematical symbols with the goal of solving for unknown quantities or variables. Algebra, along with geometry and calculus form the backbone of modern mathematics.


Astronomy refers to the study of the motion. structure, and origin of celestial bodies such as stars, planets, comets, asteroids, and moons. Many would argue that astronomy constitutes the first genuine science created by man, as various ancient cultures such as the Sumerians and Egyptians systematically organized their empirical descriptions of the stars into mathematical models that could predict astronomical data with great precision. Modern astronomy has branched out from simply studying the bodies that inhabit the larger universe but to studying the structure and composition of the universe itself. The branch of astronomy concerned questions about the universe itself is called cosmology.


The term axon refers to the long slender portion of a mammalian neuron that connects and conducts electrical signals between the neurons. Electrical impulses from an axon are sent to other parts of the brain and body. Axons differ from dendrites which are the web-like portions of individual neurons that conduct electrical signals to the main body of the neuron.

Absolute Zero

Absolute zero refers to a temperature that is the theoretical coldest temperature possible. Since temperature is defined as the motion of molecules, a temperature of absolute zero would correspond to absolutely no motion in atoms (except for random quantum fluctuations.which are impossible to eliminate). On traditional temperature scales, absolute zero corresponds to -469.57° F and -273.15°C. The Kelvin scale of temperature takes absolute zero as its starting point, assigning that temperature a value of 0°K.