Those words don't exist. It's a good bet that Tamriel lacks the established social concepts as well.
There is evidence of every manner and combination of sixual behavior, and no reason to belief that Tamriel's mortals function any differently. Leave it to the Altmer to have some perversely inconceivable custom regarding sixuality, however.
I'd bet good money the Altmer are vehemently against homosixuality. For a race that tries to transcend mortality via eugenics, the idea of (physical) love existing for anything other than procreation would be completely alien to them.
To that end, I'd expect that the Altmer probably have customs involving some form of arranged marriage. Any Altmer "unlucky" enough to be born gay would probably be married to a member of the opposite six against his will (though he'd probably admit it's for the good of his people) and would be forced seek out a homosixual relationship the same way we humans were (and in some sad cases, still are): in secret.
I imagine social attitudes of homosixuality in the Summersets to be similar to during the McCarthy-era United States: http://en.wikipedia.org/wiki/Societal_attitudes_toward_homosixuality#McCarthy_era
(Like I said, breeding away mortality would be something quite important to the Aldmeri Dominion, so a "you're with us or you're against us" mentality seems pretty likely)
Of course, this is all speculation, but given the mindset of the (more traditional) Altmer, it's probably not far off, IMO.