Everythign can be a liquid if held at the appropriate temperature and pressure. Liquids are generally thought of as fluids, and may or may not be considered wet although wetness is distinctive to liquids. Liquids flow into containers and around obstacles, but do not naturally fill all available space because they are liquids and not gasses.
Liquids do not exist in space. If a liquid is placed into outerspace (or any other vacuum) it will either freeze into a solid, or evaporate into a gas. It is very important that all liquid-based life forms avoid situations where they may come into direct contact with space (or any other vacuum.)