flat1 S2 W2 comparative flatter, superlative flattest
smooth and level, without raised or hollow areas, and not sloping or curving:
houses with flat roofs
a perfectly flat sandy beach
The countryside near there is flat as a pancake (=very flat).
Work on a clean, flat surface.
a flat rate, amount of money etc is fixed and does not change or have anything added to it:
Clients are charged a flat rate of £250 annually.
We charge a flat fee for car hire.
a flat tyre or ball has no air or not enough air in it
not very deep, thick, or high, especially in comparison to its width or length:
The cake came out of the oven flat, not fluffy.
a drink that is flat does not taste fresh because it has no more bubbles of gas in it [≠ fizzy]
a performance, book etc that is flat lacks interest, excitement, or energy:
not interesting[not before noun]
Arsenal looked flat for large parts of the game.
a flat battery has lost its electrical power [= dead American English]
Have you checked that the batteries haven't gone flat (=become flat)?
if prices, economic conditions, trade etc are flat, they have not increased or improved over a period of time:
Analysts are expecting flat sales in the coming months.
a musical note that is one semitone lower than the note E, B, A etc [↪ sharp, natural]
if a musical note is flat, it is played or sung slightly lower than it should be [≠ sharp]
not showing much emotion, or not changing much in sound as you speak:
'He's dead,' she said in a flat voice.
a refusal etc that is definite and which someone will not change:
Our requests were met with a flat refusal.
to be lying down so that all of your back is touching the floor
to be very ill so that you have to stay in bed for a period of time:
I've been flat on my back with the flu all week.
flat shoes have very low heels
having little variety of light and dark:
Flat lighting is typical of Avedon's portraits.
16 British English spoken old-fashioned
used to say that you will definitely not change what you have just said [= and that's that]:
I won't go, and that's flat!