1. (疾病、残疾)慢性的，长期的
    A chronic illness or disability lasts for a very long time.

    e.g. ...chronic back pain.
           慢性背痛

2. 难以根除的;积习难改的
    You can describe someone's bad habits or behaviour as chronic when they have behaved like that for a long time and do not seem to be able to stop themselves.

    e.g. Anyone who does not believe that smoking is an addiction has never been a chronic smoker.
           不相信抽烟能上瘾的人肯定不是老烟民。
    e.g. ...a chronic worrier.
           总是忧心忡忡的人

3. (局势或问题)严重的，顽固的
    A chronic situation or problem is very severe and unpleasant.

chronic在线翻译

    e.g. One cause of the artist's suicide seems to have been chronic poverty...
           那位艺术家自杀的一个原因似乎是极端贫困。
    e.g. There is a chronic shortage of patrol cars in this police district.
           这个治安辖区严重缺乏巡逻车辆。