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What does a- mean in medical terms?

a-

Meaning: without, not, absence of

Type: Prefix

A prefix goes at the very start of a word, before the root. On this page: what a- means, and real medical words that use it, each broken down into its parts.

Example words using a-

asymptomatic
a- (without) + symptomatic (showing symptoms) = without symptoms
apnea
a- (without) + pnea (breathing) = temporary absence of breathing
aseptic
a- (without) + septic (relating to infection) = free from infection-causing microbes

More prefixes

ab-ad-allo-ambi-amphi-an-ana-aniso-ante-anti-apo-auto-

Shortened forms

Charts and notes shorten long terms — see the Medical Abbreviations guide for the short forms you will meet in real records.

Please note: This section teaches the language of medicine — what word parts mean and how terms are built. It is an educational reference, not medical advice. For the meaning of a word in your own medical record, ask the clinician who wrote it.