is a specific kind of: domestic partner, significant other, spousal equivalent, spouse equivalent | relation, relative.

is a broader term that covers: bigamist | consort | helpmate, helpmeet | hubby, husband, married man | monogamist, monogynist | honeymooner, newlywed | polygamist | married woman, wife.

is a member of: man and wife, marriage, married couple.

derivation: copulate, couple, mate, pair | spousal.