A pandemic is defined as the "worldwide spread" of a new disease.
It's the first time the coronavirus has been declared a pandemic with more than 100 thousand cases globally and thousands of deaths.
Director-General Tedros Ghebreyesus said he isn't using the word lightly but it is a pandemic that can be controlled.
"We're deeply concerned both by the alarming levels of spread and severity and by the alarming levels of inaction. We, therefore, have made the assessment that COVID-19 can be characterised as a pandemic," he said.
The World Health Organization says people with mild illness recover in about two weeks, while those with more severe illness may take longer to get better.
