matrimonium

from Bouvier's Law Dictionary, Revised 6th Ed (1856)
MATRIMONIUM. By this word is understood the inheritance descending to a man, 
ex parti matris. It is but little used. 
     2. Among the Romans this word was employed to signify marriage; and it 
was so called because this conjunction was made with the design that the 
wife should become a mother. Inst. 1, 9, 1. 
    

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