We don't have synonyms for montgolfiers yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are montgolfier and mongolfier.
(n) :
(dated) Ellipsis of Montgolfier balloon. [The most common type of hot-air balloon, a balloon lifted by only heated air with onboard burners, and a usually-manned platform at the base.]
(n) :
(dated) Ellipsis of Montgolfier balloon. [The most common type of hot-air balloon, a balloon lifted by only heated air with onboard burners, and a usually-manned platform at the base.]