1. Steel with a surface that is much harder than the interior metal

Type of: steel

• inflation
• inflation rate
• inflation therapy
• inflationary
• inflationary spiral
• inflationist
• inflaton
• inflator
• inflect
• inflected
• inflection
• inflectional
• inflectional ending
• inflectional morphology
• inflectional suffix
• inflexed
• inflexibility
• inflexible
• endemically
• endemism
• Enderby Land
• endergonic
• endermatic
• endermic
• endgame