Did you know?

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

infiltrate - 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.

Thesaurus diagram

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.

verb [intransitive/transitive]     infiltrate pronunciation in American English
/ˈɪnfɪlˌtreɪt/    infiltrate pronunciation in American English
Word Forms
present tense
present participleinfiltrating
past tenseinfiltrated
past participleinfiltrated
  1. 1
    to secretly join an organization or go into a place in order to find out information about it or damage it
    infiltrate into:

    plans to prevent rebels from infiltrating into the country

    Synonyms and related words
  2. 2
    to become a feature of something gradually, without anyone noticing

    the way that technology has infiltrated our daily lives

derived words


     infiltration pronunciation in American English
/ˌɪnfɪlˈtreɪʃ(ə)n/ noun [uncountable]
Synonyms and related words


noun [countable]
Word Forms
Synonyms and related words

deep learning

a form of machine learning which incorporates the use of neural networks

BuzzWord Article

Open Dictionary

snap election

a general election … that is called earlier than expected

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