What is the difference between 'I am of the opinion' and 'I am off the opinion'?

I was in a chat conversation with a close friend and, in quickly swiping over my keyword, made a typo, which reads:

I am off the opinion we should inform him.

What I meant was:

I am of the opinion we should inform him.

but she interpreted the negative meaning out of it. Her interpretation was that:

We shouldn't inform him.

because there was 'off', which she believed would negate the whole sentence.

So my questions are:

• Is she right in her interpretation?

• Can the 'off' in

I am off the opinion.

negate the whole sentence?

• If so, in oral communication, how do I make out if the speaker is referring to 'of' or 'off'?

I tried to Google it without luck. I could not find anything that would support her argument, nor anything that would prove she was wrong.

May be a native English speaker can help with this problem.

Solution 1:

"Off the opinion" is not idiomatic. If someone wrote that they were off some opinion, many native speakers would be inclined to seek clarification unless the correspondent was prone to odd phrasings or had great facility with metalepsis.

Nevertheless, we can read your question as asking what it would mean if the friend considered your use of “off” as intentional. The rest of this answer proceeds on that basis.

Here's the natural sense of your use of “off”, albeit figuratively in your case:

off preposition 3 So as to be removed or separated from. ‘threatening to tear the door off its hinges’ - ODO

Your friend is correct that an intentional use of “off the opinion” would be understood as a contrast to “of the opinion”. The sense is that you were previously of a particular opinion, but you are now distancing yourself from that opinion.

You also asked about how to distinguish between "of the opinion" and "off the opinion" in speech. The former is idiomatic and the latter is the marked form, so you can expect that if someone wanted to use "off" in that manner, they'd emphasise the word - perhaps saying "off" slightly louder than expected, holding the word a little longer than expected, leaving a slight pause after the word, or even spelling it out: "I am off the opinion, oh-eff-eff, ...". The enunciation might be nuanced but the human ear is remarkably capable of picking out such emphases, especially in a conversation between native speakers.