In India, the muni is a sage who has taken a vow of silence - or, more fully, onewho has understood the nature of the silence that lies beyond all words.
muni in British English2
(ˈmʊnɪ) US slang
noun
1.
a municipal bond
adjective
2.
(esp of a bond) municipal
If you're not in one of these tax brackets, stay away from municipal bonds in anyform, including muni bond funds.