Definition of hard and fastness in English:
hard and fastness
noun ˌhɑːd (ə)n(d) ˈfɑːs(t)nəsˌhɑːd (ə)n(d) ˈfas(t)nəs
The quality or condition of being rigidly laid down or prescribed; inflexibility; fixedness.
Origin
Late 19th century. From hard and fast + -ness.