‘说透’ (shuō tòu) is a compound verb meaning ‘to explain thoroughly’ or ‘to make something completely clear.’ The first character, 说 (shuō), means ‘to speak’ or ‘to explain,’ while 透 (tòu) literally means ‘through,’ ‘penetrating,’ or ‘thoroughly’ — together, they convey the idea of explaining something so fully that nothing remains ambiguous or hidden. It emphasizes depth, clarity, and completeness in communication.

This expression is commonly used in educational, professional, or interpersonal contexts when someone has clarified a complex concept, resolved a misunderstanding, or delivered a convincing explanation. It often implies effort, patience, and insight on the part of the speaker. While not formal in register, it’s more common in spoken and semi-formal written Chinese than in highly technical or literary texts. It typically follows a subject performing the action (e.g., 老师说透了这个原理) and can be modified by adverbs like 彻底地 or 把…说透 to highlight scope or object.