1. Relationship by blood rather than by marriage; relationship arising through common descent from the same man and woman, whether the descent is traced through males or females.
“ ‘Cognation’ is … a relative term, and the degree of connexion in blood which it indicates depends on the particular marriage which is selected as the commencement of the calculation.” Henry S. Maine, Ancient Law 122 (17th ed. 1901).
2. Civil law. A relationship existing between two people by blood, by family, or by both.
civil cognation. A relationship arising by law, such as that created by adoption.
mixed cognation. A relationship that combines the ties of blood and family, such as that existing between brothers who are born of the same marriage.
natural cognation. A blood relationship, usu. arising from an illicit connection.
3. Relationship between persons or things of the same or similar nature; likeness.