also: ほうしゃ
noun
borax
Chemical compound, sodium tetraborate. Used in cleaning, glassmaking, and as a flux.
ホウ砂は洗剤やガラスの原料として使われる。
Borax is used as a raw material for detergents and glass.
From the chemical name borax, via Dutch or German, with the kanji 硼砂 (boron sand) used as a direct translation.