An amacratic lens or system corrects for aberrations so that light rays originating from a single source point perfectly intersect at a common image point. This condition ensures that the focal spot is not smeared by spherical aberration. It is a historic term in lens design, largely replaced in current engineering by terms describing specific aberration corrections like aplanatic or stigmatic.
Heard on the job
The older blueprints specify an amacratic objective, so we should probably just substitute a standard aplanat.
Insider tip
While rarely used in current optical engineering discussions, you will see it in older literature describing lenses that achieve perfect point-to-point imaging.