noun
moisture content; water content
Technical term used in engineering, agriculture, food science, etc. to express the proportion of water in a material, usually as a percentage.
木材の含水率を測定する。
Measure the moisture content of the wood.
この土壌の含水率は約20％です。
The water content of this soil is about 20%.
湿度 refers to humidity in the air, whereas 含水率 is used for the water content in solid or liquid materials.
Compound of 含水 (がんすい, 'containing water') and 率 (りつ, 'rate, ratio').