topic
/ˈtɒpɪk/noun
1- a matter dealt with in a text, discourse, or conversation; a subject题目, 话题; 主题：
her favourite topic of conversation is her partner.
她最爱谈的话题便是她的伙伴。
1.1
- Linguistics that part of a sentence about which something is said, typically the first major constituent【语言学】主题。
词源
late 15th cent. (originally denoting a set or book of general rules or ideas)： from Latin topica, from Greek ta topika, literally 'matters concerning commonplaces' (the title of a treatise by Aristotle), from topos 'a place'.