岳母
yuè mǔ · HSK 7
mother
⛰️👩 岳 = mountain/peak + 母 = mother, so the towering mother = wife's mother
岳 means a high mountain or peak (also a surname); pair it with 母 mother and you get 岳母, your wife's mother. Ties to the old custom of calling the father-in-law 泰山 after Mount Tai, the great peak.
母 — pictograph of kneeling woman with two breast dots
母 is a pictograph derived from 女 (woman) with two added dots representing breasts, marking a nursing mother. The earliest oracle bone forms show a kneeling figure with prominent dots on the chest. The meaning has stayed remarkably stable, denoting 'mother' and by extension 'female' or 'source/origin'.