Beyonce and Jay Z's twins' names revealed. The son is named Sir Carter..

According to TMZ, Jay Z and Beyonce have named their twins Rumi and Sir Carter.

They said they know this because the company run by the couple that owns the trademarks to their names just filed legal docs to secure the rights to the names, Rumi Carter and Sir Carter. The trademarks are for fragrances, cosmetics, key chains, baby teething rings, strollers, mugs, water bottles, hair ribbons, playing cards, tote bags, sports balls and rattles and novelty items.