verb (used without object), o·ver·a·chieved, o·ver·a·chiev·ing.
to perform, especially academically, above the potential indicated by tests of one's mental ability or aptitude.
to perform better or achieve more than expected, especially by others.
Origin of overachieve
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
(intr) to perform (for example, in examinations) better than would be expected on the basis of one's age or talents