rounden

From round +‎ -en.

rounden (third-person singular simple present roundens, present participle roundening, simple past and past participle roundened)

1. (transitive) To make round or rounded
2. (intransitive) To become round or rounded
   • 1974, La Conchiglia, volume 6, page 9:

     This specimen shows a wide, concave and smooth fossula with a clear-cut thread tying the first tooth to the first denticle; there are still four other irregular denticles after which the inside part of the fossula sinks and roundens.

• enround