A significant feature of the family relation terminology in the Slovak language is its big cognitive value from the linguistic and extra linguistic point of view. They reflect not only an internal language development but mainly extra linguistic factors that give a possibility to identify a cultural development context in a space and time. The author pays attention to the development of two groups of words: 1st: expressing of consanguinity – nomina consanguinitatis, and 2nd: expressing of a kinship acquired by marriage – nomina afinitatis.