Definition of bug noun from the Oxford Advanced Learner's Dictionary

  1. 1[countable] (especially North American English) any small insect See related entries: Invertebrates
  2. 2[countable] (informal) an infectious illness that is usually fairly mild a flu bug There's a stomach bug going round (= people are catching it from each other). I picked up a bug in the office. Synonymsdiseaseillness disorder infection condition ailment bugThese are all words for a medical problem.disease a medical problem affecting humans, animals or plants, often caused by infection:He suffers from a rare blood disease.illness a medical problem, or a period of suffering from one:She died after a long illness.disease or illness?Disease is used to talk about more severe physical medical problems, especially those that affect the organs. Illness is used to talk about both more severe and more minor medical problems, and those that affect mental health:heart/​kidney/​liver illness mental disease. Disease is not used about a period of illness:She died after a long disease.disorder (rather formal) an illness that causes a part of the body to stop functioning correctly:a rare disorder of the liver. A disorder is generally not infectious. Disorder is used most frequently with words relating to mental problems, for example psychiatric, personality, mental and eating. When it is used to talk about physical problems, it is most often used with blood, bowel and kidney, and these are commonly serious, severe or rare.infection an illness that is caused by bacteria or a virus and that affects one part of the body:a throat infectioncondition a medical problem that you have for a long time because it is not possible to cure it:a heart conditionailment (rather formal) an illness that is not very serious:childhood ailmentsbug (informal) an infectious illness that is usually fairly mild:a nasty flu bugPatterns to have/​suffer from a(n) disease/​illness/​disorder/​infection/​condition/​ailment/​bug to catch/​contract/​get/​pick up a(n) disease/​illness/​infection/​bug CollocationsIllnessesBecoming ill catch a cold/​an infectious disease/​the flu/(British English) flu/​pneumonia/​a virus/(informal) a bug get (British English) ill/(North American English) sick/​a disease/​AIDS/​breast cancer/​a cold/​the flu/(British English) flu/​a migraine come down with a cold/​the flu/(British English) flu contract a deadly disease/​a serious illness/​HIV/​AIDS be infected with a virus/​a parasite/​HIV develop cancer/​diabetes/​a rash/​an ulcer/​symptoms of hepatitis have a heart attack/​a stroke provoke/​trigger/​produce an allergic reaction block/​burst/​rupture a blood vessel damage/​sever a nerve/​an artery/​a tendonBeing ill feel (British English) ill/​sick/​nauseous/​queasy be running (British English) a temperature/(North American English) a fever have a head cold/​diabetes/​heart disease/​lung cancer/​a headache/(British English) a high temperature/(North American English) a fever suffer from asthma/​malnutrition/​frequent headaches/​bouts of depression/​a mental disorder be laid up with/ (British English) be in bed with a cold/​the flu/(British English) flu/​a migraine nurse a cold/​a headache/​a hangover battle/​fight cancer/​depression/​addiction/​alcoholismTreatments examine a patient diagnose a condition/​disease/​disorder be diagnosed with cancer/​diabetes/​schizophrenia prescribe/​be given/​be on/​take drugs/​medicine/​medication/​pills/​painkillers/​antibiotics treat somebody for cancer/​depression/​shock have/​undergo an examination/​an operation/​surgery/​a kidney transplant/​therapy/​chemotherapy/​treatment for cancer have/​be given an injection/(British English) a flu jab/(North American English) a flu shot/​a blood transfusion/​a scan/​an X-ray cure a disease/​an ailment/​cancer/​a headache/​a patient prevent the spread of disease/​further outbreaks/​damage to the lungs be vaccinated against the flu/(British English) flu/​the measles/(British English) measles/​polio/​smallpox enhance/​boost/​confer/​build immunity to a disease See related entries: Ailments and diseases
  3. 3(also the… bug) [singular] (informal) an enthusiastic interest in something such as a sport or a hobby the travel bug She was never interested in fitness before but now she's been bitten by the bug.
  4. 4[countable] (informal) a small hidden device for listening to other people’s conversations They planted a bug in his hotel room. See related entries: Solving crime
  5. 5 [countable] a fault in a machine, especially in a computer system or program See related entries: Computer software, Computer problems
  6. Word Origin early 17th cent.: of unknown origin. Current verb senses date from the early 20th cent.Extra examples A stomach bug has been going round at school. He’s off work with a flu bug. I planted a bug to record their conversation. She’s been bitten by the travel bug. a bug in the software My computer’s really slow at the moment—it must be some kind of bug. The latest software is full of bugs. This is a particularly nasty flu bug.
See the Oxford Advanced American Dictionary entry: bug