説
せつ · setsu · JLPT N3 · noun
theory
💬 説 = 言 speech + 兑 explain: words that lay out a theory
The left side 言 marks words and speech. 説 also appears in 説明 (setsumei, explanation) and 小説 (shōsetsu, novel, literally a small telling). Sound hook: setsu, a theory that sets you thinking.