"Depth of field" (visual definition)

Cf. verbal definitions e.g. "For a given setting of an optical system (or a steady state of accommodation of the eye) it is the distance over which an object may be moved without causing a sharpness reduction beyond a certain tolerable amount. Depth of field increases when the diaphragm (or pupil) diameter diminishes as, for example, in old eyes".
https://medical-dictionary.thefreedictionary.com/depth+of+field