Noun. From Persian.
“The chattering noise made with teeth when feeling really cold or really angry”
A fantastically onomatopoeic word that (I believe) is pronounced something akin to ‘jagger jagger’ in English. The word used in the description (‘chattering’) can be seen as a one-word equivalent to this, but zhaghzhagh carries an extra bit of semantic meaning (the fact that it can be caused from temperature or rage) and the onomatopoeia allows for the accompanying sound made from the zhaghzhagh.