any feeling of illness or physical or mental change that is caused by a particular disease

He's complaining of all the usual flu symptoms - a high temperature, headache, and so on. 他说他出现了所有常见的感冒症状——高烧、头痛等。

He's been HIV-positive for six years, but just recently he's started to develop the symptoms of AIDS. 他 HIV 病毒检测呈阳性已有6年时间，但直到最近才开始出现艾滋病的症状。

any single problem that is caused by and shows a more serious and general problem

It's her feeling that the recent outbreaks of violence are a symptom of the dissatisfaction that is currently affecting our society. 她觉得最近爆发的暴力事件表明目前不满情绪正在影响我们的社会。