It means there is very little hope of making a recovery/surviving as a medical term.
estan grave. its very very bad. es - tan - gra-vey.
But very serious.
sad music (music that is grave) Mournful tunes Of Minor Melodies
He had one foot in the grave means he was very old.
Grave, solemn, earnest, grim, humorless
It is an adverb. It can mean "actually" or colloquially it can mean very (e.g. really mad).
A grave threat is a threat made very seriously.
very ill. so ill that it might seem like your going to the grave with you illness
Very
To take apart or dismantle something like when you dissect something in biology class,or in anither sense to look at something very closely
Nano = Very small.
It can either mean that someone is a coward, or it can be a gay term for a very young gay man.