hard-and-fast

[hahrd-n-fast, -fahst] /ˈhɑrd nˈfæst, -ˈfɑst/
adjective
1.
strongly binding; not to be set aside or violated:
hard-and-fast rules.
Origin
1865-70
Related forms
hard-and-fastness, noun
Synonyms
fixed, precise, inflexible, inviolable, rigorous, unambiguous.
British Dictionary definitions for hard and fast

hard and fast

adjective
1.
(hard-and-fast when prenominal) (esp of rules) invariable or strict
Idioms and Phrases with hard and fast

hard and fast

Defined, fixed, invariable, as in We have hard and fast rules for this procedure. This term originally was applied to a vessel that has come out of water, either by running aground or being put in dry dock, and is therefore unable to move. By the mid-1800s it was being used figuratively.