We don't have synonyms for trilemma yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are dilemma, epilemma and axilemma.
(n) :
A circumstance in which a choice must be made between three options that seem equally undesirable.
(n) :
A situation in which a choice must be made among three desirable options, only two of which are possible at the same time.
(n) :
(logic) An argument containing three alternatives, jointly exhaustive either under any condition(s) or under all condition(s) consistent with the universe of discourse of that argument, that each imply the same conclusion.
(n) :
A circumstance in which a choice must be made between three options that seem equally undesirable.
(n) :
A situation in which a choice must be made among three desirable options, only two of which are possible at the same time.
(n) :
(logic) An argument containing three alternatives, jointly exhaustive either under any condition(s) or under all condition(s) consistent with the universe of discourse of that argument, that each imply the same conclusion.