The amount of matter in an object is its mass. You can use the words 'heavy' and 'light' to describe the mass of an object. You can use the words 'heavier' and 'lighter' when comparing the mass of ...

If something seems very heavy for its size (like a heavy metal object), we say it is more dense. If something seems light for its size (like a bag of cotton or pumice rock), then we say it has low ...