Provide your best answer for the following question. Give ONLY the answer, no other words or explanation.
For example:

Answer: <most likely answer, as short as possible; not a complete sentence, just the answer!>.

The question is: A student describes a substance as lacking a definite shape. The description also states that the particles of matter are close to each other but still able to flow past each other. Which type of substance is the student most likely describing?
liquid
Liquid.