a-, an-

(Greek: prefix; 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.

aglossia (uh GLAHS see uh) (s) (noun), aglossias (pl)
1. Without a tongue or having no tongue: The latest style of shoe has been the aglossia.
2. The absence of the tongue that exists before or at birth: It was difficult for the calf to feed because of its congenital condition of aglossia.
3. The loss of the ability to speak; mutism: The medieval court jester was unable to talk because he suffered from aglossia.
agnathia (s) (noun), agnathias (pl)
A complete or partial absence of one or both jaws: After the accident, Sammy had partial left agnathia and so he had to learn to speak again.
agnosia (s) (noun), agnosias (pl)
1. The inability to recognize certain sensory stimuli: Because of an extensive neural damage as the result of the car accident, Paul's friend experienced aural agnosia.
2. Loss of the ability to recognize people or objects and their meanings: A tragic consequence of the industrial accident was the onset of agnosia making it impossible for some of the workers to continue working because they couldn't remember how to perform their jobs anymore.
3. In medicine, losses of comprehensions at the levels of central nervous systems of any of the senses: The sensory spheres of the agnosias may be intact, but Linda is unable to assimilate the meanings of whatever the senses indicate.
agnosis (s) (noun), agnoses (pl)
The total or partial loss of the abilities to recognize familiar objects, often resulting from brain damage: Disabilities in recognizing things may affect any of the senses and is classified accordingly as auditory, visual, olfactory, gustatory, or tactile agnosis.
agnostic (s) (noun), agnostics (pl)
1. Not known or that which is unknown; an assertion of the uncertainty of all claims to knowledge: The word agnostic was invented, or coined, by T.H. Huxley, the eminent British biologist, in his Science and Christian Tradition, published in 1870, page 21; because he felt that the existence of God was a proposition that could not be proven scientifically. So an agnostic says, in effect, "There may be a God, but as for me, I do not know."
2. A person who believes that the existence of God is unknown, but does not deny the possibility that God exists: Sherman, who was an agnostic, was not convinced that there is a God; however, he also was open to considering any evidence that would prove that God is a reality.
3. Someone who thinks it is impossible to know whether there is a God, future life, or anything beyond the material phenomena we are experiencing and who is unwilling to accept supernatural revelation: One dictionary defines an agnostic as being someone who is not, as is often held, someone who doesn’t know whether there is a God, but a person who believes it is impossible to know or to prove anything about the existence of God.

An agnostic is someone who says he knows nothing about God, and when you agree with him, he becomes angry.

—Evan Esar

An agnostic is someone who has no invisible means of support.

—John Buchan
agonic (adjective), more agonic, most agonic
Characteristic of not forming an angle; having no angle: The line indicating the perimeter of a circle is an agonic line.
agrammaphasia (s) (noun), agrammaphasias (pl)
Ungrammatical speech: Agrammaphasia is a form of aphasia, in which Susan, with this disability, forms words into a sentence without regard for any of the grammatical rules.

Agrammaphasias are usually caused by a cerebral disease that is characterized by an inability to construct a grammatical or intelligible sentence while still having the ability to speak single words.

agrapha (s) (noun), agraphas (pl)
Sayings attributed to Jesus Christ but which are not recorded in the Bible but found in other early Christian writings; literally, "no writing": The Biblical scholar studied not only the texts of the Bible but the agraphas which were located in other sources.
agraphesthesia (s) (noun), agraphesthesias (pl)
The inability to recognize letters or numbers drawn by examiners on the skin of the subjects who are being tested: In agraphesthesias, the patients' eyes are often closed when these procedures are performed on the skin areas that are normally visible to them so they can't see what the examiners are doing.

When a person with agraphesthesia can't feel "writing" on the skin, it is believed that it is usually caused by a central nervous system lesion. This problem is typically tested by an examiner who uses an instrument [not an ink pen nor a pencil] that forms a number in the palm of one of the hands, which the patient can't see, and then asking that person to tell what the number is.

When blindfolded, Robin experienced total agraphesthesia, and could not recognize any of the simple designs the doctor drew on the palm of his hand.

agraphia (s) (noun), agraphias (pl)
1. Loss of the ability to write, resulting from neurological damage such as a brain lesion: After Mable's severe head injury, she experienced agraphia and so she was incapable of communicating with a pen or a pencil.
2. Being incapable of writing properly which can be a result of aphasia and alexia that is caused by lesions in various portions of the cerebrum; especially, those in or near the angular gyrus of the brain or that part of the brain that is involved in the processing of auditory and visual input and in the comprehension of language: After many medical examinations, the doctors determined that the agraphia experienced by Bryant was neurologically different from that which might have resulted from an injured arm.
agraphic (adjective), more agraphic, most agraphic
Characteristic of a loss of the power, or the inability, to communicate ideas in writing: Ann's agraphic disorder involved her inability to use or to understand written language because of a brain lesion.
agraphognosia (s) (noun), agraphognosias (pl)
The inability to identify numbers or letters traced on the palm (or other parts of the body surface): Helen Keller did not experience agraphognosia so she was able to learn to write when her teacher traced numbers and letters on her palm.

Helen Keller (1880-1968) was a United States lecturer and writer who was blind and deaf from the age of 19 months as a result of a severe fever. Anne Sullivan taught her to read, to write, and to speak and since she was not hampered by agraphognosia, Helen even graduated from college with honors and went on to become an activist and lecturer in support of blind and deaf people.

ahydrotaxis (s) (noun), ahydrotaxes (pl)
Organisms or creatures that spontaneously move away from moisture or wet conditions: There are some ahydrotaxes in nature that are intolerant of or can't exist very long in water or even in prolonged wet or damp environments.
ahypnia (s) (noun), ahypnias (pl)
Sleeplessness or being unable to sleep: Angelina often had a condition of ahypnia that resulted in keeping her from sleeping, so she had to take sleeping pills on many occasions.

There are many people who are suffering from various forms of ahypnia.

alalia (s) (noun), alalias (pl)
Speechlessness; loss of the ability to talk: As a result of an earlier trauma, Muriel had to live with alalia and so she learned to communicate by writing instead of speaking.