1
general::
Phrase(s): flat as a pancake
Go to *flat as a board and *flat as a pancake
McGrawhill's American Idioms And Phrasal Verbs
2
general::
Extremely level, especially too much so. For example, There are no hills; this terrain is flat as a pancake. This simile dates from the 1500s and has survived its contemporary, flat as a flounder. It is sometimes used, either disparagingly or ruefully, to describe a small-breasted woman.
American Heritage Idioms