A flat is a set of rooms for living in, usually on one floor and part of a larger building. A flat usually includes a kitchen and bathroom.

Something that is flat is level, smooth, or even, rather than sloping, curved, or uneven.

Flat means horizontal and not upright.

A flat object is not very tall or deep in relation to its length and width.

Flat land is level, with no high hills or other raised parts.

A low flat area of uncultivated land, especially an area where the ground is soft and wet, can be referred to as flats or a flat .

You can refer to one of the broad flat surfaces of an object as the flat of that object.

Flat shoes have no heels or very low heels.

A flat tyre, ball, or balloon does not have enough air in it.

A flat is a tyre that does not have enough air in it.

A drink that is flat is no longer fizzy.

A flat battery has lost some or all of its electrical charge.

If you have flat feet, the arches of your feet are too low.

A flat denial or refusal is definite and firm, and is unlikely to be changed.

If you say that something happened, for example, in ten seconds flat or ten minutes flat, you are emphasizing that it happened surprisingly quickly and only took ten seconds or ten minutes.

A flat rate, price, or percentage is one that is fixed and which applies in every situation.

If trade or business is flat, it is slow and inactive, rather than busy and improving or increasing.

If you describe something as flat, you mean that it is dull and not exciting or interesting.

You use flat to describe someone's voice when they are saying something without expressing any emotion.

Flat is used after a letter representing a musical note to show that the note should be played or sung half a tone lower than the note which otherwise matches that letter. Flat is often represented by the symbol after the letter.

If someone sings flat or if a musical instrument is flat, their singing or the instrument is slightly lower in pitch than it should be.

If you say that something is as flat as a pancake, you are emphasizing that it is completely flat.

If you fall flat on your face, you fall over.

If an event or attempt falls flat or falls flat on its face, it is unsuccessful.

If you say that you are flat broke, you mean that you have no money at all.

If you do something flat out, you do it as fast or as hard as you can.

You use flat out to emphasize that something is completely the case.

On the flat means on level ground.