科目 (kēmù) means 'subject'—specifically an academic subject taught in school or tested in exams, such as mathematics, history, or biology. The character 科 (kē) originally referred to a branch or category (as in science or examination division), while 目 (mù) means 'item' or 'category', reinforcing the idea of a distinct, classified area of study. Together, they form a compound noun that emphasizes formal, institutionalized fields of learning.

This word is used almost exclusively in educational contexts: students choose subjects for their curriculum, teachers assign grades per subject, and national exams list required subjects. It does not refer to general topics of conversation or informal interests (for which you’d use 话题 huàtí). 科目 is neutral in register and common in both spoken and written Chinese, especially in schools, official documents, and exam-related discussions.