IPA: /ˈɡaɪd.laɪn/
KK: /ˈgaɪdˌlaɪn/
A guideline is a rule or piece of advice that helps people decide how to act or what to do in certain situations.
The teacher provided a set of guidelines for the project to help students understand what was expected.
Guideline → It is formed from "guide" (from Old French *guider*, meaning to lead or direct) and "-line" (from Latin *linea*, meaning a line). The word "guideline" refers to a line or principle that directs or leads someone in their actions or decisions.
Think of a 'line' that helps you 'lead' or 'direct' your actions — that's what a guideline is.