計器
けいき · keiki · JLPT N3 · noun
meter
🌡️ 計器 = measure + instrument, so a tool that measures
計 (kei) means to measure or count, as in 時計 (tokei, clock). 器 (ki) means a tool or container, as in 楽器 (gakki, musical instrument). Put them together and you get a measuring instrument: a meter or gauge.