Undertenancy is a legal term that refers to a rental agreement between a tenant and a subtenant. There are several synonyms for the word which include subletting, subleasing, subrenting, subtenancy, and suboccupancy. Subletting occurs when a tenant allows another person to occupy their entire rental property during their absence, granted they have permission from their landlord. Subleasing refers to the process of a tenant renting out a portion of their rented space to another party. Similarly, subrenting involves a tenant subletting a portion of their rented space. Lastly, suboccupancy refers to the act of a person living in rented accommodations under the rental agreement of the tenant.