An Etymological Dictionary of Astronomy and Astrophysics

General: A flaw or defect.
Detectors: Latent imperfections in the photodiodes (pixels) of a solid-state detector.

Etymology (EN): From O.Fr. blemiss “to turn pale,” extended stem of blemir, blesmir “to injure, make pale.”

Etymology (PE): Âk “defect, blemish,” Mid.Pers. ak, âk “evil, harm,” Av. aka- “bad, wicked;” cf. Skt. aka- “pain , trouble.”