We don't have synonyms for calyx yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are calx, calix and caly.
(n) :
a cup-like structure in the mammalian kidney; collective term for the sepals of a flower, i.e. the outermost whorl of flower parts, when this is not the same in appearance as the next such whorl (the corolla)
(n) :
a cup-like structure in the mammalian kidney; collective term for the sepals of a flower, i.e. the outermost whorl of flower parts, when this is not the same in appearance as the next such whorl (the corolla)