guideline
1. [ noun ] guidance relative to setting standards or determining a course of action
Related terms: line guidance
2. [ noun ] a detailed plan or explanation to guide you in setting standards or determining a course of action
Synonyms: road_map
Examples:

"the president said he had a road map for normalizing relations with Vietnam"

Related terms: plan guidance
3. [ noun ] a light line that is used in lettering to help align the letters
Related terms: line
4. [ noun ] a rule or principle that provides guidance to appropriate behavior
Synonyms: guidepost rule_of_thumb
Related terms: rule