Description:

The term 'papam' comes from Old Common. Davidson might have chosen it as onomatopoeia. Its core meaning is thunder, the atmospheric. 

Noun: 

In a noun context, papam refers to thunder the atmospheric phenomenon and can sometimes be extended metaphorically to refer to any loud, deep noise, like a roar.

Verb: 

The base, original meaning of papam in a verb context is as an avalent zresu verb meaning to thunder (which ordinarily also implies lightning without having to mention it). It has subsequently acquired an avalent up shift to a happat verb of communication where papam conveners conveys a very loud, generally low pitched manner of speech, like a roar, with an ergative speaker or source, an absolutive thing said and a dative audience. 

Modifier: 

The derived modifier form 'papamys' has a sense like 'thundering', having a loud, low pitched rumbling quality like thunder.