灯台
とうだい · toudai · JLPT N2 · noun
beacon
灯台 = 灯 light + 台 stand: a light on a stand, by the sea
台 means stand or platform, as in 台所 (daidokoro, kitchen). A 灯台 is a light set on a tower along the coast to guide ships.
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'.
台 — mouth 口 + 厶 (private)
Originally depicted a raised platform or terrace, suggesting elevation and a place to stand. The character later extended to mean stage, podium, or station. In modern usage it also serves as the simplified form of 臺 (platform) and 颱 (typhoon), and names Taiwan (台灣).