Did you know?

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

act as - 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.

phrasal verb [transitive]
Word Forms
present tense
I/you/we/theyact as
he/she/itacts as
present participleacting as
past tenseacted as
past participleacted as
  1. act as someone/something to do the job of a particular kind of person or thing

    You speak Greek – will you act as interpreter?

    Body fat acts as an insulator.

See also main entry: act

Open Dictionary


a rise in the level of a stream or river

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