Aberr

Aberr is a shorthand term encountered in technical literature as an abbreviation for aberration. The word derives from Latin aberratio, meaning deviation or wandering away, and is used across disciplines to describe departures from an ideal reference. In many contexts, aberr is not a distinct concept on its own but a contracted label used in formulas, diagrams, and notes to indicate a defect, error, or imperfection in measurement, imaging, or perception.

In optics, optical aberrations arise when a lens or imaging system fails to bring all rays from a point source to a single convergence. Common types include spherical aberration (outer portions of a spherical lens focusing differently from central regions), chromatic aberration (different wavelengths refracted to different focal planes), coma (off-axis point sources appearing comet-shaped), astigmatism (two perpendicular focal lines), field curvature, and geometric distortion. Correcting aberrations is central to lens design and imaging science, using aspheric elements, achromatic doublets, coatings, and sometimes computational post-processing.

In astronomy, stellar aberration refers to the apparent displacement of stars due to Earth's motion relative to the speed of light. Discovered by James Bradley in 1728, annual aberration reaches about 20.5 arcseconds and traces a small elliptical path over the year. Aberration corrections are essential for precise astrometry and navigation.

Notes: the term aberr is primarily a convenience in technical writing and is seldom treated as a separate concept apart from aberration itself. See also aberration, aberrant.