AS flat as a pancake ?

as old as the hills

as hard as iron

as good as gold

as green as grass

as warm as toast
Simply write "very" + the adjective.

Very flat.
Very old.
I'm guessing here that you are asking what these commonly heard phrases mean. The writer, in these examples, assumes that the reader, knows what a pancake is, what hills are, iron, grass, and toast. And he/she uses these objects with a descriptive term (flat, old, hard, good, green, warm) that is naturally associated with them, in order to illustrate a quality about something else that is like them. "That moth-eaten coat he's wearing is as old as the hills."

There's a lot more of them that are common, which I'm sure EnglishForward readers can offer up, for the fun of it. One which I never quite understood: "As easy as pie." I don't know if that means as easy as baking a pie, or as easy as eating one. For me eating it is a lot easier than baking it.
Site Hint: Check out our list of pronunciation videos.
Additionally, these are all clichéd similes, which are good as gold for verbal communication, but which should be avoided like the plague in formal writing.
Students: We have free audio pronunciation exercises.
For sure, MrM.

How about: "avoid it like the plague"? I bet you know a thousand of them.

I'd like to hear George Carlin do a stand-up monologue using nothing but cliched similes
very well ! thank you again for your understandingEmotion: smile