The term 'hardest and strongest' can be summarized by the word 'steeliest', which has nine letters. Steel is an alloy of iron and carbon, and is known for its strength and durability. It is used in a variety of applications, from construction to automotive manufacturing. Steel is also one of the most recycled materials on the planet, making it an environmentally friendly choice. Steel is often used in the production of tools and weapons, as it is able to withstand high levels of stress and strain. In conclusion, steeliest is an apt description for the term 'hardest and strongest'.