(in England) a suit or dress for formal occasions

Usage examples of balldress.

He watched as she picked up the hem of an imaginary balldress and swept him an elaborate formal court curtsey that ended in her gracefully sweeping almost to the floor.

Yes, either that or Nicola in low-corsaged opal balldress and elbow-length ivory gloves, with a sable-trimmed brick-quilted dolman, a comb of brilliants and a panache of osprey in her hair.