A more thorough explanation:

Definition: A disseisor (also spelled disseizor) is a person who wrongfully takes away someone else's ownership or possession of a property.

Example: John bought a house and started living in it. However, after a few months, his neighbor, Tom, claimed that the house belonged to him and started living in it. Tom is a disseisor because he wrongfully took away John's possession of the property.

Explanation: The example illustrates the definition of disseisor as Tom wrongfully deprived John of his freehold possession of the property. John had bought the house and was living in it, but Tom's claim and subsequent occupation of the property without any legal right made him a disseisor.