hard - high
- hardened steel
- hardener
- hardening
- hardening accelerator
- hardening bath / trough
- hardening crack
- hardening delayer
- hardening furnace
- hardening layer
- hardening power
- hardest burned brick
- hardness
- hardness / hardness-drop tester; hardometer
- hardness number
- hardness penetration
- hardness-testing machine
- hards
- hardware
- hardwood
- hardy
