Severe means very serious and hard to bear. Severe weather, severe pain, a severe shortage.
It is the standard grading word in weather warnings, medicine and damage reports — mild, moderate, severe. Of a person or a punishment it means strict and harsh: a severe expression, a severe sentence. Of a style it means plain to the point of bareness: severe lines, a severe haircut. Note severely, which is common before adjectives and participles: severely damaged, severely limited.
1adjectivesevereVery serious and hard to bear.
“There was a severe shortage of everything that winter.”
2adjectivestrictStrict and harsh.
“The sentence was severe and widely criticised.”
3adjectiveplainPlain to the point of bareness.
“The building has severe lines and no decoration at all.”
Too few real examples of this word to estimate which sense is commonest.
severe is a degree of seriousness.
Latin severus meant grave and serious in bearing. It is unrelated to sever, which comes from separare — the two words simply look alike in English, which catches people out.
Proto-Indo-European
*seǵʰ-
Latin
severus — severe, serious, grave in demeanor
English, today
severe
From Middle French -, from Latin severus (“severe, serious, grave in demeanor”).
Etymology from Wiktionary, CC BY-SA