fastnessPronunciation: /ˈfɑːs(t)nɪs/Definition of fastness noun 1a secure place well protected by natural features:a remote Himalayan mountain fastness 2 [mass noun] the ability of a material or dye to maintain its colour without fading or washing away:the dyes differ in their fastness to lightOrigin: Old English fæstnes (see fast1, -ness)fastness in other Oxford dictionaries Definition of fastness in the US English dictionary
