abbreviation for no appreciable disease. (1) NAD. Medical humour No abnormality discovered An abbreviation that may be voiced to an attending (US) or consultant (UK) which may in fact mean that the requested procedure or test was 'not actually done' by the house officer (US) or houseman (UK). Medspeak No acute distress.he symbols for the oxidized and reduced forms are NAD and NADH. nicotinamide-adenine dinucleotide phosphate (NADP) a coenzyme similar to nicotinamide-adenine dinucleotide but involved in fewer reactions.