Kenneth G. Wilson (1923–). The Columbia Guide to Standard American English. 1993.
chronic (adj.)
means “long-lasting, recurrent, constant, or habitual,” and in American English it should not be used as an intensifier meaning “bad or severe.” Chronic headaches recur, but they may or may not be severe headaches as well. The Oxford English Dictionary has evidence suggesting that chronic may be a British slang intensifier, but in American English such use would be Substandard.
