[ˈfɑːs(t)nəs], (Noun)

Definitions:
- a secure place well protected by natural features
(e.g: a remote Himalayan mountain fastness)

- the ability of a material or dye to maintain its colour without fading or washing away
(e.g: the dyes differ in their fastness to light)


Phrases:

Origin:
Old English fæstnes(see fast, -ness)