Are Not Faultless Meaning?

: having no fault : irreproachable faultless workmanship.

Are not interchangeable meaning?

: not capable of being interchanged : not interchangeable noninterchangeable parts.

How can I use faultless in a sentence?

She was absolutely faultless at it, never ever making a mistake. The soprano soloists in the latter are very good tho not faultless . On a 100-mile journey up the motorway, the Rover proved faultless . Effectively losing his discard, he would have to sail a near faultless regatta to regain his crown.