inform

UK: /ɪnˈfɔː^rm/ US: /ɪnˈfɔrm/ ,(in fôrm′)

WordReference Random House Learner's Dictionary of American English © 2025

in•form¹ /ɪnˈfɔrm/   v. 

1. to give knowledge of a fact to (someone);
   tell: [~ + object]
   We informed them, so they should have come.
   [~ + object + of/about + object]
   We informed them of our arrival. We informed them about our plans.
   [~ + object + (that) clause]
   We informed the press that the president had arrived.
2. to give information indicating that someone has committed a crime, as to the police:
   [~ + on/against + object] informed on the other members of the gang.

See -form-.

WordReference Random House Unabridged Dictionary of American English © 2025

in•form¹  (in fôrm′), v.t. 

1. to give or impart knowledge of a fact or circumstance to:
   He informed them of his arrival.
2. to supply (oneself ) with knowledge of a matter or subject:
   She informed herself of all the pertinent facts.
3. to give evident substance, character, or distinction to;
   pervade or permeate with manifest effect:
   A love of nature informed his writing.
4. to animate or inspire.
5. [Obs.]
   • to train or instruct.
   • to make known;
     disclose.
   • to give or impart form to.

v.i. 

6. to give information;
   supply knowledge or enlightenment:
   a magazine that entertains more than it informs.
7. inform on, to furnish incriminating evidence about (someone) to an authority, prosecuting officer, etc.:
   He informed on his accomplices.

• Latin, as above
• Middle French enfourmer
• Latin infōrmāre to form, shape, equivalent. to in- in-² + fōrmāre to form; replacing Middle English enfourmen
• Middle English informen 1275–1325

in•form′a•ble, adj. 
in•form′ing•ly, adv. 
Synonyms

• 1. apprise; notify, advise, tell.
• 2. acquaint.

in•form²  (in fôrm′), adj. [Obs.]

1. without form;
   formless.

• Latin informis formless, deformed, equivalent. to in- in-³ + -formis -form
• 1545–55

Collins Concise English Dictionary © HarperCollins Publishers::

inform / ɪnˈfɔːm/ verb

1. (tr; often followed by of or about) to give information to; tell
2. (tr; often followed by of or about) to make conversant (with)
3. (intr; often followed by against or on) to give information regarding criminals, as to the police, etc
4. to give form to
5. to impart some essential or formative characteristic to
6. (transitive) to animate or inspire

Etymology: 14th Century: from Latin informāre to give form to, describe, from formāre to form

inˈformable adjective