Azimuth vs Yaw? What is the difference between these two terms, or are they completely synonymous? I have frequently seen either used in connection with pitch and roll.

There are others probably more qualified to speak on this subject than I, but from what I've gleaned from the Wikipedia pages on Azimuth and Yaw:

Azimuth seems to be used to represent an absolute heading, while yaw is a measurement of how much a craft turns from its current orientation.

Thus, if your azimuth went from $90^\circ$ to $184^\circ$, your yaw was $94^\circ$, while your current azimuth is $184^\circ$.