Lease Agreement: An arrangement between two or more parties in which the lessor (landlord) agrees to lease property, such as an office building, to the lessee (tenant) for a predetermined period of time. This agreement outlines the responsibilities and rights of both parties, and is a legal binding document that must be adhered to for the duration of the lease. Lease agreements provide tenants with security and peace of mind, as any breach of their conditions can lead to swift eviction.