Goiter is usually caused due to lack of iodine, used to make thyroxin, a hormone secreted by the thyroid gland to regulate the body's basal metabolic rate (how fast the body uses energy from food). If there is not enough iodine, the thyroid gland will enlarge to capture as much iodine out of the bloodstream as possible.
Goiter is usually painless, but makes you sluggish and causes weight gain. It also causes cretinism in children if the mother had goiter during pregnancy.
Goiter was widespread in the plains states during the 1930s, due to the lack of iodine in the in-land diets. (iodine is common in seafood). This problem was for the most part solved by the iodization of salt.
Sea salt loses its iodine in the drying process, and so is not a good natural source of iodine. If you are worried about your iodine intake, use iodized sodium chloride instead.
Webster (not our Webster1913) says that the word goiter may have its roots in the Latin guttur, meaning throat, or crop of a bird. Goiter is also known as Bronchocele or Derbyshire neck.