Word To Use Today: nark.

 Nark is a British, Australian and New Zealand word.

It's not vulgar, exactly, though I doubt you'd hear the Queen using it, or any but the trendiest possible vicar.

A nark is usually a police informer, but it can also mean to annoy or irritate someone (it's usually found in a form like: I was really narked by him turning up at the party wearing his football shirt, I can tell you). 

In Britain (though I've never come across this usage myself) a nark can also describe someone who keeps on and on and on complaining. In Australia and New Zealand a nark can be a spoilsport.

None of this is pleasant, but then nark is a good word for expressing powerful feelings of annoyance and disgust.

I feel a similar word was probably used by the fiercer dinosaurs when some animal they were hoping to eat for dinner made it to the swamp.

Nark!

 Word To Use Today: nark. No one is quite sure about the origin of this word, but it might be something to do with the Romany word nāk, which means nose.