Tamsyn

Thomasina, Thomasine, or Thomasena is the feminine form of the given name Thomas, which means "twin". Thomasina is often shortened to Tamsin. Tamsin can be used as a name in itself; variants of Tamsin include Tamsyn, Tamzin, Tamsen, Tammi, Tamzie and Tamasin. The version "Tamsin" is especially popular in Cornwall and Wales. Along with Tamara it is the ancestor of "Tammy".