学期 (xuéqī) means "semester" or "school term," referring to one of the divisions of an academic year. Chinese schools typically have two semesters per year. It is commonly used in phrases like 每学期 (every semester) and 上学期 (last semester).
这个学期我选了五门课。
Zhège xuéqī wǒ xuǎn le wǔ mén kè.
I chose five courses this semester.
上学期她去法国做了交换生。
Shàng xuéqī tā qù Fǎguó zuò le jiāohuànshēng.
Last semester she went to France as an exchange student.
每学期开学前都要交学费。
Měi xuéqī kāixué qián dōu yào jiāo xuéfèi.
Tuition has to be paid before the start of each semester.