inform

inform — verb

1. to give someone facts or details about something, so that they know what is happ

1.verbtransitiveB1
Definition

to give someone facts or details about something, so that they know what is happening or what has happened

Example

The school sent a letter to inform parents about the new safety rules.

inform + someone + about + something

Christopher informed his manager that the project would need more time.

inform + someone + that-clause

Common collocations
  • inform someone about
  • inform someone of
  • inform someone that
  • keep someone informed
  • duly inform
  • formally inform
  • inform the public
  • inform parents
Synonyms
  • tell

    more general and less formal; can be used in everyday conversation

  • notify

    more official, often in writing; implies a formal obligation to pass on information

  • advise

    adds a layer of recommendation or guidance alongside the information

  • update

    focuses on bringing someone current with the latest developments

Antonyms
  • conceal

    to keep information hidden from someone

  • mislead

    to give someone false or wrong information

Grammar Patterns

inform + someone + about + something

inform + someone + of + something

inform + someone + that-clause

Usage Note

Often used in official or written contexts. When the information is a full statement, use a that-clause; when it is a topic, use about or of. Inform someone of is slightly more formal than inform someone about.

Common Mistakes

I informed him the news.
I informed him of the news.
Inform requires a preposition (of/about) or a that-clause before the information, not a second direct object.
She informed me that she will arrive late.
She informed me that she would arrive late.
Reported speech after inform typically uses backshifted tenses in formal English.

2. to tell the police or someone in a position of authority that another person has

2.verbintransitiveB2
Definition

to tell the police or someone in a position of authority that another person has done something wrong

Example

Feng informed on his business partner after discovering the fraud.

inform on + someone

A member of the gang informed against its leader to the police.

inform against + someone

Common collocations
  • inform on someone
  • inform against someone
  • inform to the police
  • inform to the authorities
  • secretly inform
  • anonymously inform
Synonyms
  • report

    more neutral; can be used for any situation without the negative connotation of betraying trust

  • tell on

    informal; common among children or in casual settings

  • rat on

    very informal and derogatory; suggests betrayal

Antonyms
  • cover up

    to hide wrongdoing instead of reporting it

  • protect

    to shield someone from being reported or found out

Grammar Patterns

inform + on + someone

inform + against + someone

Usage Note

Always followed by on or against when naming the person reported. Never takes a direct object of the person being reported — the structure is always inform on/against + person. Inform against is less common and sounds more formal or legal.

Common Mistakes

He informed the police his neighbor.
He informed on his neighbor to the police.
To report someone's wrongdoing, use inform on/against + the person, not a direct object.
She informed on the crime.
She informed on the person who committed the crime.
Inform on takes a person, not an activity or event.

3. to have a strong influence on the way something develops or is understood — for

3.verbtransitiveC1
Definition

to have a strong influence on the way something develops or is understood — for example, how a person's background shapes their opinions, or how research guides policy decisions

Example

Her experiences as a refugee inform her writing about displacement and home.

The director's research on climate change informed the government's new policies.

active: research informs policy

Common collocations
  • be informed by
  • deeply informed
  • strongly informed
  • informed by experience
  • informed by research
  • informed by values
Synonyms
  • shape

    more concrete and widely used; emphasises giving form or direction

  • influence

    broader and more neutral; can be weaker or stronger in effect

  • guide

    suggests direction and purpose, often with positive intent

  • mould

    less common; implies actively shaping or forming

Grammar Patterns

be informed by + something

something informs something

Usage Note

Common in academic, intellectual, and professional writing. The subject is usually an abstract noun such as experience, research, values, tradition, or culture. The passive construction (be informed by) is particularly frequent.

Common Mistakes

The teacher informed the lesson with new ideas.
The teacher's approach was informed by new ideas.
In this sense, inform is used for abstract influences, not for the act of telling someone during a lesson.
Phrasal verbs

inform on

phrasal verb

To give information about someone's secret or illegal activities to an authority.

Maya decided to inform on her colleague for stealing office supplies.

Did the witness inform on the suspect during the trial?

Word family

Synonym discussion

Sense: verb/1

Tell is the most general and neutral word of the group — it can be used in any context, from casual conversation to formal reporting. Notify is more official and usually involves written communication or an obligation to pass on information, as in 'notify the authorities of a change of address.' Advise adds a layer of guidance or recommendation alongside the information, making it appropriate when the speaker has some expertise. Update focuses on bringing someone up to date with the latest developments, often implying a continuing relationship. For example: a doctor tells you test results but advises you on treatment options; a school notifies parents of a closure but updates them on reopening plans.

tell ↗notify ↗advise ↗update ↗

Etymology

LatinFrenchEnglish

Inform comes from the Latin verb informare, meaning 'to shape, give form to'. It was formed from in- ('into') and forma ('form, shape'). In Latin it first meant 'to give shape or character to something' — a meaning that survives in modern sense 3 (SHAPE OR INFLUENCE). By late Middle English, the word had developed the meaning 'to give information to' (sense 1), which grew from the idea of 'forming the mind' through knowledge.