Collins Russian Dictionary 2nd Edition © HarperCollins Publishers 2000, 1997:
balloon [bəˈluːn] n возду́шный шар; (also: hot air balloon) аэроста́т; (in comic strip) ко́нтур, в кото́рый впи́сываются ре́плики геро́ев ко́миксов
* is used to mark translations which have irregular inflections. The Russian-English side of the dictionary gives inflectional information.
Русский: