used of the degree of something undesirable e.g. pain or weather
"The severity of the winter storm made travel nearly impossible."
something hard to endure
"the asperity of northern winters"
extreme plainness
"The severity of his facial expression made him look more stern than angry."
excessive sternness
"severity of character"
"the harshness of his punishment was inhuman"
"the rigors of boot camp"
The state of being severe.
"The severity of the winter storm caused power outages across three states."
In plain English: Severity means how bad, serious, or intense something is.
"The severity of the winter storm made everyone stay indoors all day."
The word severity entered English via the Middle French form severite, which itself came from the Latin sevēritās. It originally carried the same meaning as it does today, describing strictness or harshness.