Abstract: A plastic container comprises a bottom wall, a side wall extending upwardly and laterally outwardly from the bottom wall, and an undulating rim extending laterally outwardly from an upper portion of the side wall. The undulating rim forms a plurality of waves extending at least partially around the upper portion of the side wall. Each wave forms a crest and a trough that are generally perpendicular to an adjacent section of the upper portion of the side wall. In response to exerting a tensile load on the rim, the undulating rim acts like an accordion or spring and effectively increases the perimeter along an outer trimmed edge of the rim. In particular, the waves allow the rim to flatten, thereby reducing the hoop stress generated by the tensile load. By relieving the hoop stress on the outer trimmed edge of the rim, the tendency of the rim to crack or break is minimized.