'grave' means 'very serious'. Often used to describe someone who is very sick. For example, "she was gravely ill", or "her condition is grave, we think she might die soon."

不知道grave disease啥意意思，你要不指的是Graves disease吗？意思是葛雷夫斯病，医学术语就是甲状腺机能亢进、突眼性甲状腺肿。你是学医的？

Grave has a meaning :"墓穴",So 'grave disease' means 'serious ill' .if some one has grave disease,we think she or he might die soon.