The legal state of being married.
Ecclesiastics talk of the "holy" state of matrimony.
In popular culture, Gilbert O'Sulivan's song "Matrimony" refers to this legal term:
"You and me are all that matters
Disregard the rest
Trust your soon to be old man,he knows what is best
Very shortly now there's going to be an answer from you then one from me
That's matrimony
Marriage - the joining together of the two people
For better or for worse, 'til death them do part."