A state of matter
in which the item has no definite shape, but it does have a definite volume, which separates it from a gas
. It also expands and takes on the shape of its surrounding container
It's molecularly the middle stage between solid and gas. You can imagine gas as millions of separated molecules, while liquid is those molecules strung together on a chain. Solid would be those chains linked with other chains, and the molecules bonding to more molecules.
For years, glass was assumed to be a liquid, a very, very slow moving liquid. The reasons were that the molecular structure of glass was very movable, and in old cathedrals the stained glass was thicker at the base, meaning maybe it collected there over time.
The theory was disproved when a historian concluded that the glass was thicker at the base because of the way glass was made then, and the thicker end went at the bottom to be a better base. Thanks, Popular Science.