Wow, all these arguments are pretty much over semantics.
Again, proper terminology would be:
50A, 240v, 1 phase, 3 wire circuit to a 14-50R (receptacle)
To be more specific:
Provide 50A/2p circuit breaker with 3#8, #10gnd.-1"C. to a 14-50R receptacle.
Connect complete.
The term (120v) should never be mentioned as it is inferred and will only confuse the issue. The electrician does not care how the receptacle will be used, only what he needs to provide. There is no such thing as a 50A/2p 120v breaker, it will always be referred to as 240v.