Subject: Is it possible to have an electric motor that has only one pole?

My thinking on this is the fact that as an electric motor increases in speed 
it's efficiency decreases. This I am assuming is from friction and from the 
constant push pull of the two different poles. What I am wondering is that once 
the motor is going would it be possible to drop a pole and use only one pole
(North or South) to either push or pull it rather then doing both (pushing and 
pulling) which may cause a decrease in efficiency?

Re: Is it possible to have an electric motor that has only one pole?