<unk>  is one of the four principal states of matter. A<unk>  is a fluid that can freely form a distinct surface at the boundaries of its bulk material. The surface is a free surface where the<unk>  is not constrained by a container.
Liquid
Aqueous solution
Flammable liquid
Lipodissolve
Cathartic
Acid-fast
Inhalant
Biopolymer