Rotation as a vector
Zapboy says, in message 6731:
"Rotation, commonly referred to as angular velocity ... "
"Ay, there's the rub ..." as Willy said in his famous "To be, or not to be, ..."
In fact even if "rotation" were commonly equated to "angular velocity", that would make it a common error, not a common truth !!
Just as in linear kinematics there exists (at least) 3 quantities of:
displacement, velocity, acceleration,
so too there exist the same 3 kinematic equivalents in angular kinematics.
It is shoddy to say the word "rotation" is identical to any ONE of these, for "rotation" is a generic word covering all three.
The initial question used "rotation" as "angular displacement", and this is NOT a vector.
Zapboy merely reiterates a well known fact, that "angular velocity" (along with "angular acceleration" - and higher derivatives) is a vector.
Zapboy does not clear up the muddiness in the initial question.