This term is derived from the Latin for 'bald' or 'smooth', and refers to the part of the forehead between the eyebrows. This is where glabellar lines (known colloquially as 'frown lines') may develop. Glabellar lines are among the mimic wrinkles caused by the muscles of facial expression, and are usually treated with botulinum toxin. Further information on treatment of lines and wrinkles can be found here: Wrinkle treatment.