‘所长’ (suǒ zhǎng) is a compound noun meaning ‘director’ or ‘head’ of a research institute, laboratory, or other formal institutional unit—especially in scientific, governmental, or academic settings. The first character 所 (suǒ) literally means ‘place’ or ‘institution’, often used as a suffix for organizations (e.g., 研究所 yánjiū suǒ ‘research institute’). The second character 长 (zhǎng) means ‘leader’ or ‘head’, pronounced with the third tone here (not cháng). Together, 所长 specifies the person in charge of such an institution.

This title is formal and respectful, commonly used in official documents, introductions, and workplace contexts. It is not used for private companies (where 总经理 zǒngjīnglǐ or CEO is typical), nor for schools (where 校长 xiàozhǎng applies). While gender-neutral, it’s often followed by the person’s surname (e.g., 王所长 Wáng Suǒzhǎng) when addressing or referring to them directly.