抱怨 (bào yuàn) is a verb meaning 'to complain' — expressing dissatisfaction, frustration, or criticism about a person, situation, or outcome. The first character 抱 (bào) literally means 'to hold' or 'to carry', and here it functions figuratively to indicate 'holding onto' negative feelings; the second character 怨 (yuàn) means 'resentment', 'grievance', or 'bitterness'. Together, they convey the idea of carrying resentment inwardly or voicing it outwardly. It's commonly used in everyday spoken and written Chinese to describe mild-to-moderate complaints — not as strong as 控诉 (kòngsù, 'to accuse formally') but more direct and personal than 发牢骚 (fā láosāo, 'to grumble').

抱怨 often appears with subjects like people ('he complains'), situations ('she complains about the weather'), or abstract causes ('they complain about slow service'). It can be followed by 关于 (guānyú, 'about'), 对 (duì, 'toward'), or a clause introduced by 说 (shuō). While it carries a slightly negative connotation — suggesting the speaker may be overly critical or unwilling to solve problems — it’s neutral in register and widely acceptable in informal and semi-formal contexts.