Why are Solids, Liquids and Gases called Solids, Liquids and Gases?

Question: Why are Solids, Liquids and Gases called Solids, Liquids and Gases?
- Keywords:
  gas,
  liquid,
  solid
Asked by stellamaris123 to Ed, Hayley, Jason, Nathan, Sophie on 19 Mar 2013.
- Sophie Holles answered on 19 Mar 2013:
  
  Don’t know, like why is a computer called a computer or why is a mug called a mug? You could look at the root of language.. most of our words evolved from ancient greek and latin, but that doesn’t explain why the greeks associated things with those words in the first place!

Question: Why are Solids, Liquids and Gases called Solids, Liquids and Gases?