alpha; A, α +

1. Relating to or being in alphabetical order: Joan's teacher told her to sort the lists in alpha order.
2. Concerning the designation of the first in order of importance or discovery: The alpha test is the trial run of a machine or other product carried out by a developer before it is released to the public. .
3. In astronomy, referring to a some bright star: The alpha of a constellation is normally the brightest star, like the alpha star Sirius in the constellation Canis Major.

1. The first letter of the Greek alphabet: Alpha is represented in the English alphabet as "a".
2. In computer science, the first test version; a description of the first working version of a new hardware or software product or upgrade: Some features of the product may not be implemented in the alpha version and the discovery of significant bugs is usually anticipated.
3. An animal or a person that is socially dominant: In the group of thieves, Greg was the alpha followed by Tim, the second most important member.
4. An Indication of the first of a series of radiations or emissions: Alpha rays, andalpha particles, for example, are arranged in order of increasing frequency.

A drug that stops the stimulation of alpha-adrenergic receptors at the nerve endings of the sympathetic nervous system: Judy read about alpha adrenergic blockers that functions by hormones with adrenaline-like characteristics.

1. The first and last; signifies God's eternity: This idiom and its meaning, based on the first and last letters of the Greek alphabet, appears in the New Testament (Revelation 1:8): "I am Alpha and Omega, the beginning and the ending, saith the Lord," where it is repeated three more times.
2. The basic meaning of something; the crucial part; the most important aspect of something: Alpha and omega is the importance of the beginning and the end, the first and the last.

Sally had to master the alpha and omega of the new computer program before she could even begin.

A reference to the sequence of a stimulus leading to motor behavior via a simple sensorimotor path: "Beta arc" refers to arousal of higher cortical paths by the functioning of an alpha arc; thus, leading to a "sensation" rather than simple "awareness", and not by an outside stimulus directly.

The term alpha arc is approximately equivalent to "immediate response" in Watson's behavioristic psychology, while the term "beta arc" is roughly equivalent to Watson's delayed response or implicit behavior.

In astronomy, the principal star in the constellation of Centaurus; the third brightest star in the heavens: Dick found out that Alpha Centauri was the nearest of the stars that one can see without a telescope.

A radioactive decrease by emitting an alpha particle: In alpha decay, an alpha particle (two protons and two neutrons) is emitted from a nucleus and the atomic number decreases by two to form a new nucleus.

An example would be when an atom of uranium isotope of mass 238, on emitting an alpha particle, becomes an atom of thorium, mass 234.

The statistical error made in testing a hypothesis when it is concluded that a result is positive, but it really is not: When the mammogram was performed, a false positive was the result that unnecessarily frightened Mary.

A spiral arrangement of amino acids in certain protein molecules: Alpha helices form cylinders with side groups projecting outward.

A stable form of iron below 910°C (1670°F): Alpha iron is the common allotrope of iron, unchanging below 770 degrees and having a cubic crystalline structure and magnetic properties.

The positively charged, high-energy, particles emitted from the nucleus of a radioactive atom: Alpha particles consist of two neutrons and two protons and so they are identical to the nucleus of a helium atom and are one of the products of the spontaneous disintegration of radioactive elements, such as radium and thorium.

The process of emission, alpha decay, transforms one element into another, decreasing the atomic (or proton) number by two and the atomic mass (or nucleon number) by four.

It is a product of disintegration of various isotopes of both natural and artificial radioactive elements.

In Greek grammar, a prefix having negaitive or privative force, as in atheos, "godless".

A-, an-, as prefixed to terms or stems of Greek or Latin origin, often means "apart from" or "not concerned with"; for example, an amoral approach to economics is one that is "not concerned with moral issues".

Ionizing radiation including a stream of alpha particles: Alpha rays consist of radioactive, positively charged particles, two protons and two neutrons, that are ejected at high speeds in certain atomic disintegrations.

A pattern of slow brain waves:Alpha waves take place in normal people when they are at rest with closed eyes and thought by some to be associated with an alert but daydreaming mind.

The alpha rhythm is the normal brainwave in the electroencephalogram of a person who is awake and relaxed.
An alpha rhythm is a pattern of smooth, regular electrical oscillations in the human brain that occur when a person is awake and relaxed.

As recorded by the electroencephalograph, alpha waves have a frequency of 8 to 13 hertz.

In electroencephalography, the alpha rhythms,pertain to the rhythmic oscillations in electric potential occurring at an average rate of 10 per second.

A star-like formation in a photographic emulsion: An alpha star consists of short heavy tracks identifying the paths of slow alpha particles emitted from a radioactive element.