fastness

fastness
noun

a secure refuge, especially a place well protected by natural features
（尤指天然的）庇护所，避难所
a remote Himalayan mountain fastness.
一处偏僻的喜马拉雅山落脚地。
[mass noun]the ability of a material or dye to maintain its colour without fading or washing away
（材料或染料的）色牢度
the dyes differ in their fastness to light.
这些染料的耐光性各不相同。

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