Late 19th century. From muff + -y. Compare earlier muffit and mufty mid 19th century; earliest use found in Edward Bulwer-Lytton (1803–1873), writer and politician. From muff + -y.
Definition of muffy in US English:
muffy
(also muffie)
nounˈmʌfi
Scottish
The whitethroat, Sylvia communis.
adjectiveˈmʌfi
Resembling a muff.
Origin
Late 19th century. From muff + -y. Compare earlier muffit and mufty<br>mid 19th century; earliest use found in Edward Bulwer-Lytton (1803–1873), writer and politician. From muff + -y.