strict
adj.
characterized by strictness, severity, or restraint
Synonym: nonindulgent
adj.
rigidly accurate; allowing no deviation from a standard
rigorous application of the law|a strict vegetarian
Synonym: rigorous
adj.
(of rules) stringently enforced
hard-and-fast rules
Synonym: hard-and-fast
adj.
incapable of compromise or flexibility
Synonym: rigid
adj.
severe and unremitting in making demands
an exacting instructor|a stern disciplinarian|strict standards
Synonym: exacting, stern