a light line that is used in lettering to help align the letters
"The calligrapher drew a faint guideline across the paper before writing her name to ensure perfect alignment."
a rule or principle that provides guidance to appropriate behavior
"The company established a strict guideline requiring all employees to wear safety vests while working on the construction site."
A non-specific rule or principle that provides direction to action or behaviour.
"The manager shared a general guideline about maintaining open communication, but she did not specify exact steps employees must follow."
In plain English: A guideline is a general rule that suggests how to do something without being strict about it.
"The company provided clear guidelines for employees to follow when working from home."
Usage: Use guideline when referring to flexible recommendations rather than strict rules, as it implies guidance without mandatory enforcement. This distinguishes it from terms like regulation or mandate which require specific compliance.
From guide + line.