We don't have synonyms for bass guitars yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are bass guitar.
(n) :
A long-necked and solid-bodied stringed instrument (chordophone), tuned to produce bass or low notes, usually with a fretted fingerboard and four thick strings, and requiring the use of an amplifier.
(n) :
A long-necked and solid-bodied stringed instrument (chordophone), tuned to produce bass or low notes, usually with a fretted fingerboard and four thick strings, and requiring the use of an amplifier.