Oladub:

I don't know of any decision that struck down a gay marriage ban based on a definition in a dictionary. Instead, states have been unable to demonstrate a legitimate government interest advanced by banning homosexual marriage. To be sure, the definition has changed as society's attitudes have changed, but the dictionary is not a primary source of legal authority.

As for polygamous and familial same-sex marriages, i don't know what effect the recent rulings will have because they involve separate issues. Polygamy concerns the government's interest in limiting the number of mariage partners, while familial marriage concerns its interest in limiting mariage because of familial relationship. No such issues arise in the recent rulings. Moreover, polygamous are traditionally heterosexual, so i see no legal relationship between gay mariage and polygamy. If polygamy violates due process and equal protection, it does so regardless of the legality of same sex marriage.