Fortrable

To be very strong and like a fortress.

He is very fortrable.
No one could get past the fortrable goalie's defence.

Fortunable

To be weak and have no similarity to a fortress. (Fort-un-able)
Opposite of Fortrable.

Often used as a backhanded compliment as it can be misinterpreted as to be lucky or fortuitous.

The man who won the lottery looked very fortunable, weak and unstable.

congratulations on winning the lottery, I was about to buy that ticket, you are very fortunable.