The term Shemitah:
The term Shemitah is found in Devarim 15/2 with regards to the command of Shemitas Kesafim, abolishing loans. It means to let go or forgive. The term is not used in any of the earlier commands discussing the laws relating to the land during the Shemitah year. Rather the term “Shabbos” or “Sheviis” is used in the wording of these commands. Nevertheless the custom today is to use the term Shemitah to refer to the 7th year regarding all of its related matters and laws.