Answer is: solid wood.
There are five fundamental states of matter (gas, liquid, solid, plasma and Bose–Einstein condensate).
In solid, molecules are closely packed, stiff and do not changes of shape or volume. Solid object (in this example wood) does not take on the shape of its container.
Liquids (in this example water) have definite volume, but no fixed shape.
Gases (in this example nitrogen and neeon) not have definite volume and fixed shape, it depends on its container.
