Which two terms are synonymous with squatter rights?

The terms synonymous with squatter rights are "adverse possession" and "easement by prescription." Adverse possession refers to the legal doctrine that allows a person to claim ownership of land under certain conditions, typically requiring continuous and open use of the property without the permission of the original owner for a statutory period. This is essentially what squatter rights are centered around: the ability of a squatter to gain legal ownership of property they've occupied.

Easement by prescription is somewhat similar but pertains to the right to use someone else's land. This also requires continuous and open use but does not lead to ownership, rather a right to make limited use of the property.

Other options do not adequately correspond to the concept of squatter rights. For instance, ownership rights and title by deed pertain to formally recognized ownership and cannot be equated to squatter rights. Likewise, joint tenancy and tenancy in common are forms of property ownership arrangements that do not relate to the unauthorized possession of land. Liens and encroachments are legal terms relevant to different property issues and do not reflect the notion of squatter rights. Thus, the correct pairing of terms effectively describes the legal implications and conditions under which squatter rights are recognized.