Todd Pattist wrote

The term is correctly used for both the intentional flight
maneuver that you think he's thinking of (alternating motion
on the roll axis without corresponding yaw) and the dynamic
instability problem you describe below.

Neither of my three Flight Instruction manuals, Jeppesen, FAA,
and Kershner make any mention of a "Dutch Roll" co-ordination
maneuver.

From http://www.mountainflying.com/adverse2.htm

Adverse Yaw - 2
TRAINING MANEUVER
(This is sometimes improperly called a "Dutch roll")
A training maneuver, called the training roll or coordination roll,
is often introduced early during primary flight training to teach
the pilot to cope with adverse yaw. It is mostly forgotten after
the private certificate is obtained. Many instructors consider the
training roll maneuver to be of greater importance in teaching some
one to fly than chandelles, lazy eights, or other commercial pilot
maneuvers. A pilot getting into a different airplane can determine
the amount of rudder that is required for proper coordination with
the ailerons by using this maneuver.
-------------------------------------------------------------------

From William Kershner's "The Flight Instructor's Manual"

And, for Pete's sake, don't call this maneuver a "Dutch roll."
Dutch roll, a stability and control term, is a condition of a
coupling of lateral-directional oscillations with the nose yawing
as the airplane rolls from bank to bank; the object here is to
keep the nose on the point."
--------------------------------------------------------------------

Bob Moore