The phrase "grave depression" is correct and usable in written English.
It can be used to describe a severe or serious state of depression, often in a clinical or psychological context.
Example: "After months of struggling, she was finally diagnosed with grave depression, which required immediate treatment."
Alternatives: "severe depression" or "major depression."
After he died, the British press wrote that he had suffered from grave depression.
Pop said the suicide was the result of a "very grave depression" and said "it is possible" that it was related to the Ceausescu trial.
Exclusion criteria were widespread pain, prior neck trauma, rheumatoid arthritis, drug or alcohol abuse, overweight, and grave depression.
The gravity of the refugee crisis greatly compounds the impact of the six years of Greece's grave economic depression and a long summer of political instability.
Today's crisis may be the gravest since the Depression, but global finance will not be remade in a five-hour powwow hosted by a lame-duck president after less preparation than many corporate board meetings.
"The Interestings" is an ambitious, decades-spanning novel, and it touches on plenty that is grave: cancer, cults, autism, depression, the 2008 financial crisis.
It is hard - awful - to imagine him in the grip of a depression so grave that he had to be admitted to hospital.
While we may have escaped a grave economic fate (second depression), however the economy is still limping towards normalcy, and the unemployment rate has remained static.
A graduate of Fordham Law School, he was, by 1933, running his own firm and specializing in bankruptcy law, a Depression-era "grave dancer".
Paul Mortimer-Lee, head of market economics in the London office at BNP Paribas, said the move reflected concerns that the financial markets now appeared to be facing their gravest problems since the Depression.
By the time "the real thing" had seen his brilliant future both realized and ruined, he had entered the valley of extreme emotional fragility, of depressions so grave that by February of 1961, after the first of what would be two courses of shock treatment, he found himself unable to complete even the single sentence he had agreed to contribute to a ceremonial volume for President John F. Kennedy.
