理事 (lǐshì) means 'director,' 'board member,' or 'council member' and refers to a person who serves on a governing body. It often appears as part of compound terms like 理事会 (council) or 理事国 (council member state).
她是公司董事会的理事之一。
tā shì gōngsī dǒngshìhuì de lǐshì zhī yī.
She is one of the directors on the company's board.
这次会议有十五位理事出席。
zhècì huìyì yǒu shíwǔ wèi lǐshì chūxí.
Fifteen directors attended this meeting.
他担任理事已经超过十年了。
tā dānrèn lǐshì yǐjīng chāoguò shí nián le.
He has served as a director for over ten years.