Answer: hardandfast

AnswerCrossword Clue
HARDANDFASTStringently enforced
HARDANDFASTInviolable
HARDANDFASTUnalterable, as rules
HARDANDFASTStrict.
HARDANDFASTInvariable.
HARDANDFASTRigidly binding
HARDANDFASTBinding, as a contract
HARDANDFASTStringently enforced, as a rule