No, the word infallible is an adjective. The adverb form is "infallibly" (without error).
In is the prefix for infallible.
I am always right, I am infallible.
I am infallible because I am good at softball.
His logic is infallible, but I still don't believe it.
The Pope is said to be infallible in these circumstances.
Some people regard fortune-tellers as infallible truth-tellers.
Inerrant is synonomous with infallible. The major difference is that infallible additionally means dependable, reliable, and trustworthy. Inerrant merely means without erring; making no mistakes.
No, Benedict XVI is no longer the reigning pope so is not considered as infallible.
It is difficult to say who was the most infallible out of the people below Adolf Hitler. One can argue that none were infallible, as all eventually were punished for their crimes.
Fallible
Fallible Valable
The cast of Father Tucker in Infallible - 2012 includes: Dean Packis