Impostor syndrome
Etymology
Described in 1978 by psychologists Pauline Clance and Suzanne Imes, who called it the "impostor phenomenon" in high-achieving women. "Impostor" comes from Latin "imponere" (to impose upon, deceive); popular usage shifted "phenomenon" to "syndrome."
noun phrase · /im-POS-ter SIN-drohm/
A persistent feeling of being a fraud who will be exposed, despite real evidence of competence.
What it names
The private conviction that your success is luck or deception — that you don’t truly deserve your place.
Example
Even after the promotion, impostor syndrome whispered that they’d soon figure out she didn’t belong.
Related idea
The Dunning-Kruger effect is nearly its inverse — the incompetent overrating themselves; impostor syndrome is often the competent underrating themselves.