As adjectives the difference between bittiest and zittiest
is that bittiest is (bitty) while zittiest is (zitty).
bittiest
English
Adjective
(head)
(bitty)
bitty
English
Adjective
(er)
Containing bits; fragmented
Very small
Noun
(bitties)
zittiest
English
Adjective
(head)
(zitty)
zitty
English
Adjective
(er)
(informal) Characterized by zits; pimply