the.com/wisdom tooth

means The last molar to emerge, usually in the back of the mouth, typically appearing in the late teens or twenties when a person is presumably old enough to have gained some 'wisdom.'

from The name traces back to ancient thinkers — Greek physicians called these teeth 'sophronister,' from 'sophron' meaning prudent or wise, and Latin writers picked up the same idea with 'dens sapientiae' (tooth of wisdom). The logic was simple: these molars erupt later than the others, around the age people were thought to finally arrive at maturity and good sense. English 'wisdom tooth' is a direct translation of that old Latin phrase, so the name has been riding on the same joke — tardy teeth for a tardy wisdom — for well over a thousand years.