The two characters together, 疏忽 (shūhu), create a powerful and redundant meaning: to be distant from and to overlook something. This emphasizes a significant and blameworthy lapse in attention.
In Chinese culture, which often emphasizes collective responsibility (责任心, zérènxīn) and fulfilling one's duties, 疏忽 (shūhu) is a weighty word. It's not just a personal failing but can be seen as letting down one's group, be it family, the team, or the company. A good Western comparison is the difference between “carelessness” and “negligence.” While you can be careless when making a sandwich (a minor issue), “negligence” is a legal and professional term implying a failure of a duty of care. 疏忽 (shūhu) leans much closer to “negligence.” Admitting to 疏忽 is a serious apology, acknowledging that you failed in your responsibility. It shows you understand the gravity of the situation, which is a crucial step in rectifying a mistake and restoring trust, or 面子 (miànzi), in a professional or formal setting.
疏忽 (shūhu) is used in both formal and informal contexts, but it always carries a sense of seriousness.
The biggest pitfall for learners is confusing 疏忽 (shūhu) with 马虎 (mǎhu) and 不小心 (bù xiǎoxīn).