Medical terms simplifier

EMA’s medical terms simplifier gives plain-language descriptions of medical terms commonly used in information about medicines. Communication specialists at EMA use these descriptions for material prepared for the public.

This resource focuses on side effects and other terms used in medicines information and assessments of medicines. It does not include terms that are used only rarely, nor does it cover most disease states or technical terms. 

EMA has developed the definitions in this list to help readers understand medical terms used in our information for the public. It does not provide an exhaustive list of medical terms. Definitions may differ from those given in other medical glossaries.

 

How to use EMA’s medical terms simplifier 

  • You can search for a term or click on a letter below to see terms beginning with that letter.
  • Each entry contains a short description. For some, a longer or alternative description is available by selecting the term.
  • We use ‘< >’ to indicate alternative or optional wording.

EMA’s medical terms simplifier will be updated periodically. For comments or suggestions, you can use our Medical terms simplifier comments form. 

A

  • Ablation

    procedure to burn or remove parts of <tissue> <an organ>

  • Abscess

    a swollen area where pus has collected

  • Acromegaly

    excessive growth particularly of the bones of the hands, feet and face caused by too much growth hormone <from the pituitary gland>

  • Acute

    <short-lived> <sudden> <short-term>

  • Acute coronary syndrome

    <heart> conditions such as heart attack and unstable angina <(a type of severe chest pain)> <caused by blocked blood supply to parts of the heart>

  • Agonist

    a substance that attaches to a receptor (target) and triggers an effect

  • Agranulocytosis

    very low level of a type of white blood cell <called granulocytes> <which are important for fighting off infection>

  • Alkaloids

    substances that are naturally found in plants

  • Allergen

    a substance that causes an allergy

  • Allergen challenge

    a test to measure a patient’s reaction to a defined dose of an allergen (the substance that they are allergic to)

  • Anaemia

    <low levels of red blood cells> <low levels of haemoglobin> <which can cause tiredness and pale skin>

  • Anaemia, aplastic

    when bone marrow stops producing new blood cells <causing tiredness, lower ability to fight infection and uncontrolled bleeding>

  • Anaesthetic

    a medicine <which blocks sensation> used to prevent pain and discomfort <during surgery and medical procedures>

  • Anaesthetic, general

    a medicine that can be used to prevent pain by making the patient unconscious

  • Anaesthetic, local

    a medicine that blocks out sensation to prevent pain in a part of the body <during surgery or other medical procedure>

  • Anaphylactoid reaction

    sudden, severe allergic reaction <with breathing difficulty, swelling, light-headedness, fast heartbeat, sweating and loss of consciousness>

  • Anaphylaxis

    sudden, severe allergic reaction <with breathing difficulty, swelling, light-headedness, fast heartbeat, sweating and loss of consciousness>

  • Androgen

    male sex hormone like testosterone

  • Aneurysm

    bulging and weakening of blood vessel <wall>

  • Angina attacks

    sudden pains to the chest, jaw and back, brought on by physical effort and due to problems with the blood flow to the heart

  • Angina pectoris

    pains to the chest, jaw and back, brought on by physical effort and due to problems with the blood flow to the heart

  • Angina, unstable

    chest pain caused by interruptions in the heart’s blood supply, that can occur at rest <or without an obvious trigger>

  • Angioedema

    rapid swelling under the skin <in areas such as the face, throat, arms and legs> <which can be life threatening if throat swelling blocks the airway>

  • Angioplasty

    a procedure to unblock a narrowed blood vessel <in the heart>

  • Antagonist

    a substance that blocks a receptor (target) and stops other substances attaching to it and triggering an effect

  • Antibody

    a protein in the blood that helps the body's defences by identifying and attaching to specific foreign substances including germs; [in relation to a side effect] a protein the body produces that attaches to the medicine <and can affect how well treatment

  • Anticoagulant

    a substance that prevents the blood from clotting

  • Antiemetic

    a substance that <prevents> <and> <treats> nausea and vomiting

  • Antigen

    a specific structure that the body can recognise as 'foreign' and against which it can produce an antibody

  • Antihistamine

    a <medicine> <substance> that prevents symptoms of allergy

  • Antioxidant

    a substance that can prevent damage from highly reactive molecules called ‘free radicals’

  • Anuria

    when a patient cannot make or pass urine

  • Apathy

    lack of interest or energy

  • Aphasia

    problems with use of language <including speech, understanding and reading> <because of brain damage>

  • Apheresis

    a procedure where blood is passed through an external device that removes <X> before returning the blood to the body 

  • Apnoea

    interruption of breathing; see sleep apnoea; obstructive sleep apnoea

  • Arachnoid

    one of the membranes protecting the spine and the brain

  • Ascites

    a build-up of fluid in the abdomen

  • Aspergillosis

    an infection caused by a fungus called Aspergillus

  • Ataxia

    inability to co-ordinate muscle movements

  • Atherosclerosis

    a disease in which fatty deposits build up in the arteries <which can cause blockage>

  • Atony

    lack of normal muscle <strength> <movement> <function>

  • Atrophy

    wasting away of body tissue or organ

  • Aura

    unusual visual or other sensory experiences

  • Autograft

    healthy <tissue> <bone> <skin> <….> taken from one part of the patient’s body and grafted in another

  • Autoimmune disease

    a disease caused by the body's own defence system attacking normal tissue

  • Autologous

    <tissue> <cells> from the patient's own body