Dur
Durable
Brave, courageous
Valiant
Strength of mind, bravery
Fortitude
Strong and hearty
Robust
The period of time taken by something
Duration
Noble courage
Valor
A strong point, a skill
Forte
To back up, to support
Corroborate
Not diminishing, lasting
Enduring
To be of use, to help
To gather and combine
Consolidate
Support or sympathy, unity
Solidarity