Adequate: sufficient; equal to the requirement, okay, passable, satisfactory, mediocre.
Though it not longer carries this meaning in English, adequate once meant to equalize.
The old meaning is closer to its Latin roots. In Latin the preposition ad means, to or toward. Aequus means equal. Together, these two created the Latin verb adaequare: to make equal to.
“We have no adequate ideas of infinite power.” – Noah Webster
“How often—even before we began—have we declared a task ‘impossible’? And how often have we construed a picture of ourselves as being inadequate? A great deal depends upon the thought patterns we choose and on the persistence with which we affirm them.” – Piero Ferrucci