kilogram, (kokuji)
瓩 is a Japanese-made kanji (kokuji) that specifically means kilogram. It combines the ideas of weight and a thousand, representing a thousand grams.
瓩 is a kokuji created in Japan by combining 瓦 (tile, used here to represent gram, from the first character of グラム) and 千 (thousand), to mean kilogram (a thousand grams).
Picture a roof tile (瓦) with the number 千 (thousand) stamped on it. A thousand tiles weigh exactly one kilogram.
For キログラム, the reading is the borrowed word 'kilogram' itself. Imagine a kilo of tiles (瓦) stacked in a thousand (千) neat rows: kilogram -> キログラム.
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kilogram-meter