The definition of PiALOG is the same as the definition of PiALOGUE. Since some people naturally spell PiALOGUE as PiALOG I just wanted to mention that PiALOG is an alternative spelling of PiALOGUE. PiALOG tends be a strictly American use of the word. Derivative words are PiALOGIC and PiALOGICAL to describe words, phrases, and situations that have to do with PiALOG or PiALOGUE.