Are singers musicians?

The human voice conveys pitch like any other instrument. Singers must understand and apply music theory like any other instrumentalist. The great ones do this to a high level.

It's true that some singers don't have the second part of the above. But this is also true of many guitarists and other instrumentalists.

So I say yes, singers are musicians.

So then, technically speaking Johnny Rotten is a musician?

OMG, I just realised that given our definition, that, and I can't believe I am saying this, but Yoko Ono qualifies as a, (excuse me while I throw-up!).... musician.

Man, does that leave a bad taste in my mouth!
Yuch!

What on Earth is the point of asking such a question, and what on Earth makes you suppose there is a "technical" sense of "musician" that determines the answer, or that anyone should care about?

There are musicians, and some are professional, others amateur. Some musicians are great musicians, others are merely good, and then there are bad, very bad, and awful . . .

Maybe there's a spot in there for Yoko, and Johnny Rotten