Are singers musicians?

The American Heritage® Dictionary of the English Language: Fourth Edition. 2000, states that a musician is:

...One who composes, conducts, or performs music, especially instrumental music.

Therefore, in addition to instrumentalists and singers, both composers and conductors are also musicians.

Makes sense I guess!

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!