a-, an- +
(Greek: a prefix meaning: no, absence of, without, lack of, not)
These prefixes are normally used with elements of Greek origin, a- is used before consonants and an- is used before vowels.
It affects the meanings of hundreds of words.
There are too many words that use these prefix elements to list all of them on this site; however, there are significant examples listed in this and the other units where they exist.
acrania
A partial or complete absence of the skull.
acroagnosia
Lack of sensory recognition of a limb.
adactyly
The absence of digits on a hand, or hands; or on a foot, or feet.
adermia
Without skin.
adiabatic
In thermodynamics, describing a process in which there is no transfer of heat into or out of the system in question; without loss or gain of heat.
adiadochocinesia, adiadochocinesis; adiadochokinesia,
adiadochokinesis
Loss of the power to perform rapid alternating movements. This symptom is indicative of a disorder of the cerebellum or its tracts.
adiaphoria
Non response to stimuli as a result of some previous exposure to similar stimuli.
adiathermancy
The condition of being impervious to or unaffected by heat waves.
adiathermanous, adiathermic
In physics, a reference to the inability to transmit radiant heat; not affected by heat.
adipsia
The abnormal absence of thirst; an abnormal avoidance of drinking.
adromia
The absence of impulse conduction in a nerve of a muscle.
adynamia, adynamic
1. Lack or loss of normal or vital powers.
2. Characterized by or causing weakness.
adytum
1. The sanctum in certain ancient temples which was open only to priests.
2. A private chamber; a sanctum.
3. Etymology: from Greek
a-, "not" plus Greek
dyein, "to enter".
A secret chamber or place of retirement in the ancient temples, and considered to be the most sacred spot, the innermost sanctuary, or shrine. No one but the officiating priests were permitted to enter and from which the oracles were given.
The Holy of Holies, or Sanctum Sanctorum, of the temple of Solomon was of the nature of the pagan adytum; none but the high priest was only one allowed into it, and he could go there just once a year.
Among the Egyptians the secos was the same thing, and it is described by Strabo. A well-preserved adytum that has come to our knowledge is in the little temple in Pompeii; it was raised some steps above the level of the temple itself, and it was without light.
With reference to Christian architecture, it sometimes signifies the chancel, or the altar end of a church.
—Based on information from The Catholic Encyclopedia,
Volume I; Robert Appleton Company; New York; 1907.
afebrile
1. Without fever.
2. Unaccompanied by fever.
3. Not feverish.
afetal
Without a fetus.