We don't have synonyms for transsex yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are transfer, transfix and transex.
(v) :
(intransitive) To transition (to undergo a transition) from being one sex/gender to being another (especially by sex reassignment surgery). (Compare transgender.)
(v) :
(transitive) To transgender; to (cause something to) change from being sexed/gendered in one way to being sexed/gendered in another way.
(n) :
(rare) Transsexuality, transsexualism; the state of being transsexual. (Compare transgender.)
(v) :
(intransitive) To transition (to undergo a transition) from being one sex/gender to being another (especially by sex reassignment surgery). (Compare transgender.)
(v) :
(transitive) To transgender; to (cause something to) change from being sexed/gendered in one way to being sexed/gendered in another way.
(n) :
(rare) Transsexuality, transsexualism; the state of being transsexual. (Compare transgender.)