In China, husbands often call their wives’ father "岳父 (yuèfù)." The meaning of "父 (fù) father" is rather easy to understand, but the Chinese character "岳 (yuè)" can be confusing. The following story explains why Chinese people "称呼 (chēnghū) call" their wives’ fathers "岳父 (yuèfù)":

In ancient China, emperors often went to the peaks of famous mountains to worship the mountains and rivers. Additionally, they also proclaimed promotions of other government officials there.

In the Tang Dynasty, Emperor "唐玄宗 (Táng Xuánzōng) Tang Xuanzong" promoted his subordinates at "泰山 (Tàishān) Mount Tai." He raised "张说 (Zhāng Yuè) Zhang Yue" to an official position of great power. After that, "张说 (Zhāng Yuè) Zhang Yue" used his power to help his "女婿 (nǚxu) son-in-law " "郑镒 (zhèng Yì) Zheng Yi" also get a significant government promotion. "唐玄宗 (Táng Xuánzōng) Tang Xuanzong" became aware of this and questioned "郑镒 (zhèngYì) Zheng Yi" on how he got such a good promotion in such a short time. "郑镒 (zhèngYì) Zheng Yi" remained speechless, but his colleague "黄幡绰 (Huáng Fānchuò) Huang Fanchuo" told Emperor "唐玄宗 (Táng Xuánzōng) Tang Xuanzong": "Thanks to the power of ‘泰山 (Tàishān) Mount Tai,’ he got the promotion." Then "唐玄宗 (Táng Xuánzōng) Tang Xuanzong" became to understand that "张说(Zhāng Yuè) Zhang Yue" had practiced nepotism to help his "女婿 (nǚxu) son-in-law" after his own promotion atop "泰山 (Tàishān) Mount Tai."

Many people heard of this and began to "称呼 (chēnghū) call" their wives’ father "泰山 (Tàishān) Mount Tai." Because "泰山 (Tàishān) Mount Tai" is the No. 1 among the "五岳 (wǔyuè)Five Famous Mountains," people also began to call their wives’ fathers "岳父 (yuèfù)."

In modern Chinese, this "称呼 (chēnghū) form of address" is still in use. Since Chinese people call their parents "父母 (fùmǔ)," they call their wives’ mother "岳母 (yuèmǔ)."