IT’S completely normal — and healthy — for couples to argue.

As two different people, chances are you’re going to have diverse opinions and views on various topics and situations.

But when a heated argument turns sour, what you say in the heat of the moment can have a lasting impact on even the strongest of relationships.

Sometimes, it’s easier said than done to bite your tongue, but according to one relationship expert — there’s a simple word that can diffuse an argument almost as quickly as it started.

And that magic four letter word is “ouch”.

Yes. Apparently if you say “ouch” it can put a stop to an argument in just a few seconds.

According to marriage and family therapist Hal Runkel, the word “ouch” isn’t used nearly enough during an argument — and that couples should start incorporating it in to their vocabulary.

Runkel told Business Insider that the word works well as a defence barb because if you admit something has hurt you, your partner may be more inclined to step back from a disagreement. It’s a way of showing vulnerability by revealing pain rather than anger when pushing back with a nasty one-liner.

Runkel said an exchange example may be, “Ouch. That one hurt. I don’t know if you were meaning to hurt me, I don’t know if that’s what you were going for but that is what you did.

“When [you’re] in conflict, [you’ll] inevitably say something that hurts the other person using the ‘inside information’ that you have on them or that they have on you.”

Runkel said the key is to stand strong and say “ouch” because the responding line from your partner will say a lot about your relationship.