What does the word grave mean?

These definitions come from (see link below) The Free Dictionary:
(Quick synopsis--the hole in the ground where the dead are buried, very serious, dangerous, to carve into, a back-slanting accent mark (`), a coating of pitch on the bottom of a vessel, music performed in a solemn manner)

n1. a place for the burial of a corpse, esp beneath the ground and usually marked by a tombstone Related adj sepulchral2. something resembling a grave or resting place the ship went to its grave3. (often preceded by the) a poetic term for deathhave one foot in the grave Informal to be near deathto make (someone) turn (over) in his grave to do something that would have shocked or distressed (someone now dead) many modern dictionaries would make Dr Johnson turn in his grave[Old English græf; related to Old Frisian gref, Old High German grab, Old Slavonic grobǔ; see grave3]

grave2adj1. serious and solemn a grave look2. full of or suggesting danger a grave situation3. important; crucial grave matters of state4. (Fine Arts & Visual Arts / Colours) (of colours) sober or dull5. (Linguistics / Phonetics & Phonology) (also grɑːv) Phoneticsa. (of a vowel or syllable in some languages with a pitch accent, such as ancient Greek) spoken on a lower or falling musical pitch relative to neighbouring syllables or vowelsb. of or relating to an accent (`) over vowels, denoting a pronunciation with lower or falling musical pitch (as in ancient Greek), with certain special quality (as in French), or in a manner that gives the vowel status as a syllable nucleus not usually possessed by it in that position (as in English agèd) Compare acute [8] circumflex
n(Linguistics / Phonetics & Phonology) (also grɑːv) a grave accent [from Old French, from Latin gravis; related to Greek barus heavy; see gravamen]
gravely adv
graveness n

grave3vb graves, graving, graved ; graved, graven (tr) Archaic1. (Fine Arts & Visual Arts / Art Terms) to cut, carve, sculpt, or engrave2. to fix firmly in the mind [Old English grafan; related to Old Norse grafa, Old High German graban to dig]

grave4vb(Transport / Nautical Terms) (tr) Nautical to clean and apply a coating of pitch to (the bottom of a vessel) [perhaps from Old French grave gravel]

grave5adj & adv(Music / Classical Music) Music to be performed in a solemn manner [from Italian: heavy, from Latin gravis]