规矩 (guī ju) literally combines 规 (guī), meaning 'compass' — a tool for drawing perfect circles — and 矩 (ju), meaning 'carpenter’s square' — used to draw precise right angles. Together, they symbolize standards of correctness, order, and proper conduct. Historically, the term evoked objective, measurable standards; today, it refers broadly to socially accepted rules, customs, or expected behavior in families, schools, workplaces, or traditional settings.

The word often carries a slightly formal or traditional tone and may imply unspoken expectations rather than written laws. It can describe both positive norms ('following family规矩') and negative ones ('old-fashioned规矩 that restrict freedom'). Unlike 法律 (fǎlǜ, 'law'), which is legally binding, 规矩 is more about convention and shared understanding — think of classroom etiquette, dining manners, or workplace hierarchy. It’s frequently used in phrases like 懂规矩 (understand the rules) or 没规矩 (has no sense of propriety).