课题 (kè tí) refers to a research topic, issue, or subject in academic or professional contexts — it's a formal, structured area of study or investigation. Unlike 主题 (zhǔ tí, 'theme'), which is the general subject of a work or discussion, 课题 implies a specific research question or project. It also differs from 议题 (yì tí, 'agenda item'), which is a topic for discussion in meetings or debates.