Let’s say you’re at the school gate and you hear a mother say to her boy, “Give this to Johnny’s mum”. Why not use her real name? The boy might not know it. More likely, mum has taught son that it’s impolite for him to use it.
Versions of this kind of naming by relational reference are common in societies worldwide. Anthropologists call it teknonymy (adjective teknonymous).
In some cultures, including some native American ones, it became formalised to the extent that a child's birth required the father (sometimes also the mother) to be permanently renamed according to the name given the child. Elsewhere, it may be required by etiquette or status or by social custom, often because of taboos against addressing or referring to senior members of the community by their given names. In Arabic cultures, it’s polite to refer to a married woman by the honorific Umm, “mother of” (as in Umm Khalifa, mother of Khalifa); the male equivalent is Abu (so, Abu Khalifa). Here’s another case:
Given the rather pervasive taboo in Korean culture against using personal names when speaking to or about adults, Koreans can resort to one of two interesting strategies: teknonymy or geononymy. Teknonymy is the practice of addressing or referring to an adult by way of that adult’s relationship to a child. Thus Mrs Kim, the ajumŏni next door, may also be Chinho ŏmŏni, or “Chinho’s mother.”
Korean Language in Culture and Society, by Ho-min Sohn, 2006. Geononymy, the author explains, “is the practice of qualifying kinship terms with place names.”
The word was invented by the British anthropologist Sir Edward Burnett Tylor in an article in 1888. He took it from the Greek teknon, child, plus the ending -onymy, from Greek onuma, name.