“flat”

Flat and level.

True, genuine, not merely nominal or apparent.

A bounding straight edge of a two-dimensional shape.

The same height at all places; parallel to a flat ground.

A relatively long, wide and thin piece of any material, usually wood or similar, often for use in construction or furniture-making.

To extinguish something, especially a flame, especially by means of a strong current of air or another gas.

To inflate or fill with air, either by literally blowing or by using a pump.

A person who calls attention to or complains about a flatus is likely trying to pretend it wasn't their own.

To inflate by means of a pump.