Description:

'Raz' is the Common root for 'fear'. It also has a seocnd life in its modifier form as a word that just means big or great in colloquial speech.

Verb:

As a verb, 'raz' actually means 'to frighten'. It takes an ergative thing feared and an absolutive entity experiencing fear. This verb can work a little bit like 'pex', 'know', and other 'backwards' verbs, but doesn't defy English speaker intuitions as badly if framed as 'frighten', but it actually also equally means to fear something.

The emphasis in meaning is often communicated with word order. If the speaker wants to emphasize the act of fightening an entity, the ergative subject is typically fronted, whereas to emphasize the condition of fear of the an entity towards something, the absolutive object is fronted. Examples:

Ja paluh teo raz a pikki.
The dog frightened the cat.

A pikki teo raz ja paluh.
The cat feared the dog.

The second form can also be used in an idiom of supposition or concern about a possibility, where the speaker is saying they are 'afraid' something is true (much as we can in English, the idom may actually be calqued). The thing you are afraid is true would be introduced with xi, and the verb in the dependent clause will be in the irrealis. Example:

We te raz xi ja pikki a skitrem ti slek.
I'm afraid the cat ate the mouse. [If you cared about the mouse]

Again much as in English, you can use this as a softening idiom to express a fact rather than a possibility, in which case it looks much the same except the dependent clause would be in the realis:

We te raz xi ja pikki a skitrem te slek.
I'm afraid the cat ate the mouse. [If you were informing someone else who cared about the mouse]

The pali antipassive is as with most Common antipassives idiomatically reflexive and means something like 'to frighten oneself'. The idiomatic sense is 'to be afraid' or 'to be fearful' without any source of fear specified and is often used to describe general emotional states as opposed to the response to a specific episode. Example:

A pikki sea raz.
The cat was fearful.

Some source of fear can be added using the null preposition. This is a common idiom to say that one is frightened of something but not necessarily in a state of fear of them at this very moment:

A pikki sea raz nyz paluh.
The cat was afraid of dogs.

Noun:

As a noun, 'raz' means 'fear'. Fear of something can be specified using the null preposition, so 'na raz nyz paluh' is 'fear of dogs'.

Modifier:

The derived forms razcas and razkas are easier to explain than the plain form 'razys'. 'Razcas' means 'frightening', 'terrifying', 'frightful', etc. 'Razkas' means 'fearful', 'terrified' and so on.

'Razys' itself has taken on a life of its own in slang and is so ubiquitous that it is even slipping unnoticed into more formal and official contexts. It has the plain meaning of frightening or fearful, and can actually mean either fear-inspiring or fear-experiencing depending on context. But what it has become in colloquial speech is just a word that means something is big or great, and actually has positive or approving connotations. Compare to the English word 'terrific', which has actually undergone a similar process from being a word that means that something inspires terror to a word meaning something is very good.