This question concerns 'inform on' also, and so doesn't duplicate inform about vs inform of (where user 'Maulik V' asserts the following that I edited):

Inform her of X  =  Here, we are informing her that X happened. And that is all!

On the other hand, Inform her about X
= Not only will she be informed that X happened, but also the details of X.

Yet how does inform on change all this? What of 'Inform her on X?
I already know, and so ask not, about the following ODO's definition 1.1:

inform on = 1.1. [no object] Give incriminating information about someone to ... authority


2 Answers 2


The preposition of "on" can be used to mean "to the detriment of".

The three common phrases that come to mind are "inform on", "tell on", and "tattle on", which all mean, as you say, "give incriminating information about".

I've seen "quit on". As in, if you and I are working on a project, and you quit, that hampers my efforts to complete the project. I might tell you "Don't quit on me." I might complain to someone else that "Bob quit on me."

I've also occasionally seen it used with "die". "Don't die on me!" i.e. "Don't die - I need you!"

There are a handful of other verbs it can be used with, but it's a fairly specialized use of "on". I can probably think of more verbs it can't be used with than verbs it can.


In the active voice "Inform on" is strongly associated with the meaning of criminal implication given above. However, in the passive it merely indicates an area of coverage. For example, "He is well informed on a wide variety of topics." simply indicates a person whose knowledge covers many areas.

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