Did you know?

Click any word in a definition or example to find the entry for that word

bug - definition and synonyms


What are red words?

90% of the time, speakers of English use just 7,500 words in speech and writing. These words appear in red, and are graded with stars. One-star words are frequent, two-star words are more frequent, and three-star words are the most frequent.



The thesaurus of synonyms and related words is fully integrated into the dictionary. Click on the thesaurus category heading under the button in an entry to see the synonyms and related words for that meaning.

noun bug pronunciation in British English /bʌɡ/
Word Forms
  • Facebook
  • Twitter
  1. 1
    [countable] informal an infectious but usually minor illness

    a flu bug

    get/pick up a bug (=develop an illness):

    You must have picked up a bug on holiday.

  2. 2
    [countable] computing a minor fault in a computer system or in a computer program

    The new program still has some bugs in it.

  3. 3
    [singular] informal a sudden strong enthusiasm for doing something
    be bitten by the travel/fitness/cooking etc bug (=to suddenly become enthusiastic about it):

    I’d been bitten by the back-packing bug.

  4. 4
    [countable] a small piece of electronic equipment used for secretly listening to what people are saying

    Detectives had planted (=put) a bug in his hotel room.

    Synonyms and related words
  5. 5
    [countable] informal an insect

    There were bugs crawling all over the kitchen floor.

Open Dictionary


the activity of exploring abandoned buildings and other manmade structures

add a word


A must for anyone with an interest in the changing face of language. The Macmillan Dictionary blog explores English as it is spoken around the world today.

global English and language change from our blog
Macmillan learn live love play