议题 (yìtí) refers to a topic or issue specifically put forward for discussion in a formal meeting, conference, or agenda — it's an 'agenda item'. It is more formal and structured than 话题 (huàtí, casual conversation topic) and distinct from 议程 (yìchéng), which is the agenda as a whole. Unlike 主题 (zhǔtí, theme) or 课题 (kètí, research topic), 议题 is tied to a scheduled discussion.