Occurrence of a particular disease throughout a whole country or the world. see epidemic, outbreak.

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An epidemic spanning many countries and/or several continents. The difference between an outbreak, an epidemic and a pandemic can be murky and depends on the opinions of scientists and health officials.

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A pandemic is a worldwide spread of a disease. This is a higher order of magnitude than an epidemic. In other words, an 'outbreak' is the occurrence of disease cases in excess of what's normally expected; an 'epidemic' is more than a normal number of cases of an illness, specific health-related behavior or other health-related events in a community or region; and a 'pandemic' is basically a global epidemic. Until now, the last pandemic was the H1N1 outbreak in 2009. But on March 11, the WHO declared the novel coronavirus a pandemic.

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An epidemic that has spread to multiple continents or countries. On March 11, after extensive COVID-19 spread on multiple continents, the WHO officially declared the coronavirus outbreak a global pandemic.

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When a disease has rapidly spread across many nations, the World Health Organization makes the determination whether it is has risen from epidemic to the level of a pandemic – meaning it has spread across a large international region or worldwide. On March 11, the WHO declared COVID-19 a pandemic.

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The worldwide spread of a new contagious disease that has infected a large number of people. The World Health Organization officially declared COVID-19 a pandemic on March 11, 2020. Also see related terms, “epidemic” and outbreak.”

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Pandemic is a term that refers to the global outbreak of a disease (please, don’t use "global pandemic" or "international pandemic", because it’s pleonastic!).

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An epidemic that has gone global, spreading across every continent.

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“The worldwide spread of a new disease,” according to the WHO. Differs from an epidemic by sheer scale. The WHO declared the Covid-19 outbreak a pandemic on March 11, 2020.