From Latin 'matrimonium' — literally 'the state of being a mother,' contrasting with 'patrimony' (father's inheritance).
The state or ceremony of being married; marriage, especially as a sacrament or formal institution.
From Latin 'matrimonium' (marriage, the institution of wedlock), built from 'mater' / 'matri-' (mother, from PIE *méh₂tēr — the universal Indo-European mother-word, present in Sanskrit 'mātṛ', Greek 'mētēr', Old English 'mōdor') + the suffix '-monium' (denoting a state, condition, or institution — the same suffix seen in 'testimonium', 'patrimonium'). Matrimony is therefore linguistically 'the mother-state' or 'the condition that makes one a mother' — the institution of marriage defined from the woman's perspective and her role in legitimate reproduction and inheritance. Contrast 'patrimony' (from 'pater', father) which frames inheritance from the father's side. The word entered Middle English via Old
The contrast between 'matrimony' (from 'māter,' mother) and 'patrimony' (from 'pater,' father) reveals Roman gender assumptions embedded in language. Matrimony is what marriage gives the mother — legal status and a household. Patrimony is what death gives the father's heirs — property and wealth. The mother's word governs marriage; the father's word governs inheritance.