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.
acephalia, acephalous
1. The absence of a head; having no head.
2. Having no leader or ruler.
acephalobrachia
Congenital absence of the head and arms.
acephalochiria
Congenital absence of the head and hands.
acheilia
A condition present at birth in which there is an absence of one or both lips.
acheiropody
Absence of the hands and feet.
achene
A small, dry fruit which is formed from a simple ovary bearing a single seed and that ripens without splitting its sheath open.
achondroplasia
A congenital bone disorder caused by abnormal conversion of cartilage into bone, resulting in deformities and dwarfism.
achromatic, achromic
1. Without color; colorless; unpigmented.
2. White, gray, or black in appearance.
3. Transmitting light without any constituent color separation; such as, a lens.
achromatin
The part of a cell nucleus which does not stain readily with basic dyes.
acinesia
Lack of movement.
aclusion
Absence of occlusion of the opposing tooth surfaces.
acoprosis
Absence of fecal matter from the intestine.
acoprous
Having no fecal matter in the intestine.
acoria
Absence of the pupil of the eye.
acotyledon
Any plant without seed leaves.