Merriam-Webster's Advanced Learner's Dictionary:
pancake
pan·cake /ˈpænˌkeɪk/ noun, pl -cakes [count]
1 : a thin, flat, round cake that is made by cooking batter on both sides in a frying pan or on a hot surface (called a griddle)
• We had blueberry pancakes and sausage for breakfast.
- see also potato pancake
2 : thick makeup worn especially by actors
• She wore sequins, false eyelashes, and pancake onstage.
- called also pancake makeup,
(as) flat as a pancake
- see 1flat