noun
Technical term used in chemistry and materials science to describe the ratio of void volume to total volume.
この材料の間隙率は約30%です。
The porosity of this material is about 30%.
空隙率 is a near-synonym also meaning porosity, often used interchangeably in engineering contexts, but 間隙率 may emphasize the gaps between particles or grains.
Compound of 間隙 (gap, interval) and 率 (rate, ratio).