灯泡
dēng pào · HSK 7
light bulb
💡 deng pao = lamp + bubble — a bubble of light on a lamp
灯 (deng) means lamp, 泡 (pao) means bubble or blister. A light bulb is literally a glass bubble on a lamp. The slang meaning — an unwanted third wheel — comes from 电灯泡: the awkward extra light hovering over a couple.
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'.
泡 — water radical 氵 + wrap 包
泡 is a phono-semantic compound. The water radical 氵 gives the meaning (related to liquid), while 包 (bāo, 'wrap/enclose') supplies the sound and hints at something enclosed. Originally it described bubbles—pockets of air wrapped by water—and later extended to soaking or steeping.