arduousness

I only say all this to show the tenfold arduousness of such a work as the one your problem demands.

They know the arduousness of life, which is a lesson we must all learn sooner or later.

Though not comparing with the arduousness of field service, our duties were by no means slight.

The task of the Charming Lass was delightful in its simplicity, but fearful in its arduousness.

This is done by making the hours of labor in different trades to differ according to their arduousness.