To turn over or transfer to another money or goods. To agree to recognize a new owner of a property and to pay him/her rent. In a lease, when the tenant agrees to attorn to the purchaser, the landlord is given the power to subordinate tenant's interest to any first mortgage or deed of trust lien subsequently placed upon the leased premises.
To consent, implicitly or explicitly, to a transfer of a right. Often used to describe a situation where a tenant, by staying on location after the sale of the leased property, accepts to be a tenant of the new landlord; or where a person consents to ("attorns to") the jurisdiction of a court which would not have otherwise had any authority over that person.