In polar coordinates, the Archimedean spiral is $r=\theta,\ \theta\ge0.$ Or maybe also $r= c\,\theta,\ \theta\ge0,$ where $c$ does not change as $\theta$ changes.
I found myself referring to that portion of the spiral in which $0\le\theta\le2\pi\text{ radians}$ as the "first lap", using the terminology of foot races.
Is there a standard term in geometry for that?