What type of estate is characterized by a definitive time period?

A leasehold estate is characterized by a definitive time period, making it the correct choice in this context. These estates are typically created through a rental agreement between a landlord and tenant, where the tenant is granted the right to use and occupy the property for a specified duration. This time period can range from months to years, clearly defining the term of occupancy.

Leasehold estates differ from freehold estates, which do not have a set expiration and typically indicate an ownership interest in real property. In contrast, life estates are tied to the lifetime of an individual and do not have a fixed time period beyond that life. Concurrent estates involve more than one party holding an interest in the same property, which also does not imply a definitive term of duration. Thus, the leasehold estate's focus on a specified time frame makes it the appropriate answer here.