Nous
Etymology
Greek "nous" meant mind or intellect; Anaxagoras made it the cosmic ordering principle, and Aristotle the intuitive grasp of first principles. British English later borrowed it as slang for street-smart good sense. Its loss shows in "paranoia," a mind beside itself.
noun · /nowss/
Mind or intellect — the faculty that grasps truth directly; informally, shrewd common sense.
What it names
Both the highest reasoning faculty and, in everyday British use, plain practical savvy — a telling overlap.
Example
He had the credentials but no nous — brilliant on paper, hopeless at reading a room.
Related idea
The intellect that metacognition turns back upon itself; to have nous is both to think about a problem and to see straight through it.