Mentation

\men-ˈtā-shən\

NOUN

1. A BOOKISH DEFINITION FROM BOOKISH OLD-STYLE DICTIONARY

Mental activity; thinking.

(from The American Heritage® Dictionary of the English Language, 4th Edition)

2. A MORE MODERN DEFINITION FROM THE AGE OF Y-GENERATION (INTERNET-BASED DICTIONARY)

The process of using your mind to consider something carefully.

(from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.)

According to Merriam-Webster dictionary, this word “Mentation” in use was originated in 1850)