冷れい却きゃく材ざい

れ

い

きゃ

く

ざ

い

Meanings

1

noun

Technical term primarily used for coolant in nuclear reactors; also applicable to other industrial cooling contexts.

cool, cold (beer, person), chill

却instead, on the contrary, rather

材lumber, log, timber

冷れい却きゃく水すい
冷却水 specifically refers to cooling water, while 冷却材 is a broader term for any coolant material.
冷れい媒ばい
冷媒 is used for refrigerants in cooling systems like air conditioners, whereas 冷却材 is more common in nuclear and industrial contexts.

Compound of 冷却 (cooling) + 材 (material).