We don't have synonyms for mandolins yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are mandolin, mandoline and mandolines.
(n) :
(music) A stringed instrument of the lute family, having eight strings in four courses, frequently tuned as a violin, and with either a bowl-shaped back or a flat back.
(n) :
(music) A stringed instrument of the lute family, having eight strings in four courses, frequently tuned as a violin, and with either a bowl-shaped back or a flat back.