adjective
strict
STRIKT/strɪkt/
Requiring close adherence to rules, standards, or limits.
The instructor enforces strict safety requirements before the trainee begins work.

Etymology
The image is of something drawn tight, leaving little room. The surviving sense appears to extend that tightness to rules and standards, allowing little latitude in obedience.
In context
we have very strict standards set by the EPA. And if you live in states like California, the rules set by the California Air Resources Board are even tougher.
More examples
- She's strict with her students but always treats them fairly.
- We follow a strict budget to keep our spending down.
- The factory now enforces stricter safety standards.
Forms
strict · stricter · strictest
strictly adverb — With exact adherence to rules or limits.
strictness noun — The quality of demanding close adherence.