These are all words for the state of being physically or mentally ill. 以上各词均指身体或精神上的不适、疾病。

• illness the state of being physically or mentally ill 指身体或精神上的疾病
• sickness illness; bad health 指疾病、不健康：◆I recommend you get insurance against sickness and unemployment. 我建议你办个疾病和失业保险。

illness or sickness? 用 illness 还是 sickness？

Sickness is used especially in contexts concerning work and insurance. It is commonly found with words such as pay, leave, absence and insurance. Illness has a wider range of uses and is found in more general contexts. * sickness 尤用于与工作和保险有关的语境中，通常与 pay、leave、absence 和 insurance 等词连用。illness 的用法较广，用于较一般的语境中。

• ill health (rather formal) the state of being physically ill or having lots of health problems 指健康状况不佳：◆She resigned because of ill health. 她因健康状况不佳而辞职。 NOTE Ill health often lasts a long period of time. * ill health 常持续较长时间。
• trouble illness or pain 指疾病、疼痛：◆heart trouble 心脏病 NOTE When trouble is used with this meaning, it is necessary to say which part of the body is affected. * trouble 用于此义时须说明疾病或疼痛所在的身体部位。

Patterns

• chronic illness/sickness/ill health
• to suffer from illness/sickness/ill health/heart, etc. trouble