como se dice "Ms." en espanol
Ms. is not senorita or senora.
10 Answers
Essentially Kevin and Mediterrunio have explained it nicely, so I'll just complement both answers.
The key to this was forever burnt in my mind by the stately British Grandmother of a friend of mine. The subject came up one day, and she said. "There is no such thing as Ms!" (which she prononced as "Muss", vibrating the "ss" against her teeth). "What the devil is a Muss anyway? A woman is either a Miss or a Mrs, not some sort of edible confection!"
Anyway, as Kevin explains, Ms. is simply an invention so that a woman does not have to implicitly state whether she's single or married, but in Spanish we do not make such a distinction.
As Mediterrunio states, you either use the person's plain name, Señora, or Señorita, depending on the circumstances.
It is more and more frequent in the business world to just go with the plain name. However, when addressing someone with a certain status, regardless of whether she's married or not, the custom is to call her "Señora". You'd never address the CEO of a company as "Señorita Pérez"; on the other hand, most young employees, specially if they are secretarial or clerical staff, you'll probably address as "Señorita."
I can't speak about the customs in latin america, but in Spain we don't have an equivalent of Ms, that's for sure. In a formal setting, women are always addressed as "señora" (sra.) or "señorita" (srta.).
By the way, "seño" is an abbreviation of "señora/señorita" used by small children to refer to their female teachers, regardless of their marital status. And yes, it stands alone.
Welcome to the forum. Ms. is an Englishism that doesn't have a Spanish translation.
Hola:
How about calling someone "dama"... Since there is no direct translation, this could be a polite choice.
My wife just told me that she's heard "seño" and it would stand alone w/o a name after it.
"Ms." abbreviates "Miss", meaning a unwed or young lady, which i have learned translates to señorita
Ms. is not senorita or senora.
If Ms. is not señorita or señora it must be message, which into Spanish translates as mensaje.
Now, if the rest of the answers are on the right track, I think that depending on the context (as always) you can address a woman with different expressions equivalent to Ms.
Is a formal or informal situation? Are you trying to establish a personal relation or just eliciting information? Do you just want to be polite or are you trying to catch her attention?
Sometimes it can be señora, others señorita. Most of the times you say nothing at all and in certain cases you can flatter her with a sweet word. 
Kevin is right on this one. People use it to try to be less sexist.
I haven't been able to find "seño" anywhere. I don't believe they indulge such Englishisms.
it is señorita.
