We don't have synonyms for elvin yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are elfin, kelvin and eloin.
(n) :
(Kent) Alternative spelling of elven (“an elm”) (a tree of the genus Ulmus, particularly the wych elm or Scots elm (Ulmus glabra)) [Originally, a female elf, a fairy, a nymph; (by extension) any elf.]
(n) :
(Kent) Alternative spelling of elven (“an elm”) (a tree of the genus Ulmus, particularly the wych elm or Scots elm (Ulmus glabra)) [Originally, a female elf, a fairy, a nymph; (by extension) any elf.]