As a noun mabby
is a spirituous liquor or drink distilled from potatoes; – used in the barbadoes.
As an adjective fabby is
(slang|british) fabulous, very good, excellent.
mabby
English
Noun
A spirituous liquor or drink distilled from potatoes; – used in the Barbadoes.
(
Webster 1913)
fabby
English
Adjective
(er)
(slang, British) fabulous, very good, excellent