Able to think clearly and make good decisions without confusion; having a sharp, alert mind.
Compound of 'clear' and 'headed' (from 'head,' Old English heafod). The metaphor compares a well-functioning mind to something transparent and unobstructed, dating back to the 1600s.
The phrase reveals an ancient belief that thinking works like vision—a 'clear' mind can 'see' problems just like clear eyes can see distant objects. It's the same metaphor that gives us 'blind to the truth' and 'narrow-minded.'
Complete word intelligence in one call. Free tier — 50 lookups/day.