1640s, "an error in computing time or finding dates," from Latin anachronismus, from Greek anakhronismos, from anakhronizein "refer to wrong time," from ana "against" (see ana-) + khronos "time" (see chrono-). Meaning "something out of harmony with a specified time" is first recorded 1816.
early 15c., cronik, of diseases, "lasting a long time," from Old French chronique and directly from Latin chronicus, from Greek khronikos "of time, concerning time," from khronos "time" (see chrono-). Vague disapproving sense (from 17c.) is from association with diseases and later addictions. Literal sense "pertaining to time" is rare in English. As a popular slang catch-all word for "cannabis," popularized from 1992 by "The Chronic," an album released by rapper Dr. Dre; said to be because it described especially potent marijuana, on the notion of "extreme, severe." Related: Chronical; chronically.