In medicine, describing a disease as<unk> denotes that it is of short duration and, as a corollary of that, of recent onset. The quantification of how much time constitutes "short" and "recent" varies by disease and by context, but the core denotation of<unk> " is always qualitatively in contrast with "chronic", which denotes long-lasting disease (for example, in<unk> leukaemia and chronic leukaemia). In addition,<unk> " also often connotes two other meanings: sudden onset and severity, such as in<unk> myocardial infarction (AMI), where suddenness and severity are both established aspects of the meaning. It thus often connotes that the condition is fulminant (as in the AMI example), but not always (as in<unk> rhinitis, which is usually synonymous with the common cold). The one thing that<unk> MI and<unk> rhinitis have in common is that they are not chronic. They can happen again (as in recurrent pneumonia, that is, multiple<unk> pneumonia episodes), but they are not the same case ongoing for months or years (unlike chronic obstructive pulmonary disease, which is). A noncount sense of<unk> disease" refers to the<unk> phase, that is, a short course, of any disease entity. For example, in an article on ulcerative enteritis in poultry, the author says, "in<unk> disease there may be increased mortality without any obvious signs", referring to the<unk> form or phase of ulcerative enteritis.
Acute 
Epidemic
Endemic 
Never event
Pandemic
Preiser disease
Perioperative
Infodemic