fool

fool — verb

1. to make someone believe something that is not true, usually for amusement or to

1.verbtransitiveB1
Definition

to make someone believe something that is not true, usually for amusement or to gain an advantage over them

Example

Ife completely fooled her little brother by hiding the TV remote control behind the sofa.

The car dealer tried to fool Sayaka into signing a contract with hidden fees.

fool + noun + into + verb-ing for persuasion by deception

Common collocations
  • fool someone into doing something
  • fool someone with a story
  • can't fool someone
  • fool the public
Synonyms
  • deceive

    more formal and suggests deliberate, often harmful dishonest intent

  • trick

    broader term that can include playful or harmless deception as well as mean-spirited ones

  • mislead

    focuses on giving false information rather than actively causing someone to do something

Antonyms
  • enlighten

    to give someone true information instead of false

Grammar Patterns

fool + noun phrase

fool + noun phrase + into + verb-ing

Usage Note

The action the deceived person is tricked into doing is introduced by 'into + verb-ing', not by a to-infinitive.

Common Mistakes

He fooled me to give him my money.
He fooled me into giving him my money.
the verb pattern requires 'into + -ing' form to name the tricked action.

2. to express doubt about the truth of what someone has just claimed, or to let som

2.verbtransitive / intransitiveB1
Definition

to express doubt about the truth of what someone has just claimed, or to let someone know you were only joking and not speaking seriously

Example

When Tuan claimed he was done, Élise laughed and said, "You could have fooled me!"

fixed expression 'could have fooled + object' for disbelief

"I am not fooling — I saw a bear by the school gate!" Hugo told his teacher.

Common collocations
  • could have fooled me
  • was just fooling
  • not fooling
  • only fooling
Synonyms
  • kid

    very informal, used mainly in the expression 'just kidding' instead of 'just fooling'

  • tease

    implies playful mockery rather than making someone believe something false

Grammar Patterns

could have fooled + object

was / were fooling

Usage Note

In the disbelief use, the past conditional construction 'could have fooled me' is fixed — changing the tense to 'can fool me' changes the meaning to a plain statement about ability. In the joking use, the continuous form 'was/were fooling' is standard.

Common Mistakes

You can fool me!' (to express disbelief).
You could have fooled me!
the past conditional form is a fixed expression for doubt; the present tense only describes real ability.
I fool you — the exam was easy.
I was just fooling
the exam was easy.' — the continuous form is needed for the joking meaning.
Phrasal verbs

to spend time behaving in a silly, playful, or unserious way instead of doing what you should be doing

The coach warned the players to stop fooling around and focus on their warm-up exercises.

Layla spent the whole afternoon fooling about with her cousins instead of studying for the maths test.

fool with

phrasal verb

to touch, use, or play with something in a careless way that could cause damage or danger (usually in negative commands)

The lab assistant warned the students not to fool with the chemical equipment without permission.

Amihan told her little brother not to fool with the oven settings while their mother was out of the kitchen.

fool — noun

fool — adjective

Word family

Synonym discussion

Sense: noun/1

All four words describe someone who lacks good judgment or intelligence, but they differ sharply in offensiveness and clinical history. 'Fool' is the mildest — it primarily criticises a person's judgment or behaviour in a specific situation rather than their mental ability ('I felt like a fool for forgetting'). 'Idiot' is much stronger and carries an insulting tone; it was once a clinical term for severe intellectual disability but is now widely considered offensive and ableist. 'Moron' and 'imbecile' were clinical classifications in early-20th-century psychology (moron = mild, imbecile = moderate) but are now almost exclusively used as harsh insults. In general usage, 'fool' can be self-directed or affectionate, while 'idiot', 'moron', and 'imbecile' are almost always directed at others and carry real sting. A speaker who says 'What an idiot!' is expressing stronger anger or contempt than someone who says 'What a fool!'

foolidiotmoronimbecile

Common collocations

Phrases

Prepositions

Etymology

LatinOld FrenchEnglish

The word 'fool' entered English from Old French 'fol' (meaning mad or insane), which traced back to Latin 'follis' — a bellows or leather bag filled with air. The connection between an inflated bag and a person of empty, puffed-up judgment led to its sense of a silly or unwise person. The modern English meaning as a verb (to trick) developed from the idea of treating someone as if they were a fool.