pro: /proh/ noun. 1. [ORIGIN mid 19th cent.: abbreviation.] professional. 2. [ORIGIN late Middle English: from Latin, literally ‘for, on behalf of.’] an advantage of something or an argument in favor of a course of action. A proponent.

grok: /grok/, var. /grohk/ vt. [from the novel ”Stranger in a Strange Land”, by Robert A. Heinlein, where it is a Martian word meaning literally `to drink’ and metaphorically `to be one with’] The emphatic form is `grok in fullness’. 1. To understand, usually in a global sense. Connotes intimate and exhaustive knowledge. — The Jargon File 4.2.0