灯油
とうゆ · touyu · JLPT N2 · noun
kerosene
🪔 灯 (lamp) + 油 (oil) = 灯油: lamp oil, the fuel burned in a lamp
Both characters are in the word: 灯 means lamp and 油 means oil. In Japan, 灯油 is also the kerosene used to fuel portable space heaters.
灯 — fire radical 火 + ding 丁 (phonetic)
灯 is a semantic-phonetic compound: 火 'fire' gives the meaning (lamps once burned oil or flame), while 丁 hints at the sound. It is the simplified form of the traditional 燈, which used 登 as the phonetic. Today it means 'lamp' or 'light'.
油 — water radical 氵 + 由 (yóu, phonetic)
油 is a phono-semantic compound. The 氵 radical signals a liquid, while 由 supplies the sound. Originally referring to a river name, it was extended to mean oil or fat — any thick, flowing liquid — which became its dominant modern sense.