A legal right allowing someone to enter and use another's land for a specified purpose is known as?

The appropriate term that describes a legal right allowing someone to enter and use another's land for a specified purpose is an easement. An easement is a non-possessory interest in land, which grants the holder the right to use a portion of another person's property for a specific purpose. This can include rights such as accessing a utility line, crossing a property to reach a road, or allowing shared driveways.

While a license also grants permission to use someone else's land, it is generally more temporary and can be revoked at any time, distinguishing it from the more permanent nature of an easement. A sublease refers to an agreement where a tenant leases out the property they are renting, which does not pertain to entry rights on another's property. Lastly, a right of way, while it does commonly refer to a type of easement specifically for the purpose of passing through a property, does not encompass the broader range of land use implied by the term easement itself. Thus, the definition of easement best fits the description given in the question.