1. deviation: a departure from what is normal or desirable in a moment of aberration
2. lapse: a temporary departure from somebody's normal mental state
3. optics optical defect: a defect in a lens or mirror, causing a distorted image or one with colored edges
4. astronomy apparent displacement in star's position: a small periodic change in the apparent position of a star or other astronomical object, caused by the motion of the Earth around the Sun
