TSUMUGU · B1 (est.) · 字
矩
矩 ＝ 矢 ＋ 巨
ㄐㄩˇ · jǔ
noun — a carpenter's square; a rule, standard
字源 FORM — what the parts do
矢形an arrow — here standing for the straight, true edge
巨聲jù — gives the sound AND the meaning: the L-shaped square itselfthe great square a worker once gripped, the tool that makes the right angle
Tjù → jǔ — tone lifted off the donor
巨 is itself the picture: a worker gripping the great L-shaped square, the tool that rules a true right angle. 矢, the straight arrow, marks the trueness; 巨 lends the sound, jù lifting to jǔ. From the tool comes the standard it sets: 規矩, the rules; 矩形, the right-angled shape.
故事 STORY — a scene to remember it by
工匠握著那把L形曲尺（巨），比著畫出一個正直角——矩。
The worker grips the L-square (巨) and rules off a true right angle — the standard.
字源記憶法
意 · Meanings
(本義)曲尺、矩尺— a carpenter's square
→規矩、循規蹈矩— rules, the proper standard常用
⇒矩形、矩陣— a rectangle; a matrix
(本義) original meaning · → ⇒ each arrow = one more step of extension