Liquid

Liquid was a state of matter.

On Svartos, liquid nitrogen was known as frostburn. (TV: Dragonfire)

Anti-plastic was a blue liquid that caused plastic to disintegrate. (TV: Rose, PROSE: Autonomy)

The space probe Phoenix was sent to Mars by NASA on 31 July 2008. It found liquid water on the planet. (TV: The Waters of Mars)

The Encyclopedia Gallifreya was a series of books, in the form of purple liquid in bottles, with at least eleven volumes. (TV: Journey to the Centre of the TARDIS)

Dark water was a liquid through which only organic matter could be seen. (TV: Dark Water)

The Nyathoggoth was a vampiric creature with a liquid form. (PROSE: Project: Valhalla)

The Esturians were made entirely of liquid. (PROSE: The Terror of the Thames)

The Gabrielideans were a liquid-based lifeform. (PROSE: Alien Bodies)

Arcateenians were made mostly of liquid, but adopted a humanoid form. (TV: Cyberwoman)