The Oxford Thesaurus An A-Z Dictionary of Synonyms - graveэadj.

1) serious, sombre, solemn, earnest, unsmiling, staid, sedate, sober, dour, gloomy, grim, grim-faced, grim-visaged, Brit po-faced: The doctor, looking very grave, said that he had done all he could. 2) serious, critical, vital, dangerous, matter of life and death, crucial, urgent, weighty, important, pressing, pivotal, perilous: Fenwick is in intensive care in a grave condition.