The term applies to both wheel (rim) and tyre.
Clinchers have a rim wall with a little hook on the inside of the rim wall. This hook grips the bead of the tyre when the tyre is inflated. This style of tyre/rim requires a separate innertube.
The other style of tyre/rim combination is the tubular tyre. In this instance, the innertube is sewn inside the tyre, which is then glued onto the rim.
Hope this helps.