Noun guideline has 3 senses
  1. guideline - a light line that is used in lettering to help align the letters
    --1 is a kind of
  2. road map, guideline - a detailed plan or explanation to guide you in setting standards or determining a course of action; "the president said he had a road map for normalizing relations with Vietnam"
    --2 is a kind of plan, program, programme; guidance, counsel, counseling, counselling, direction
  3. guidepost, guideline, rule of thumb - a rule or principle that provides guidance to appropriate behavior
    --3 is a kind of rule, regulation