A "lien" is what is referred to in law as a security interest which is given to a piece of property or a possession in order to secure the payment of debts or loans such as secured loans.

The person that owns the property/possession in question is the person that will grant the lien and is usually referred to as the "lienor", whereas the person that stands to benefit from the lien is called the "lienee".

The word stems from both Latin (ligament, ligare: to bind) and Anglo-French (lien, loyen: bond/restraint) and is generally used to refer to the passive right to retain (but not sell) the property in question until the issue (be it a debt or a loan) is fulfilled and the matter is discharged.

It indicates property that can actually be possessed and that when the property is lost, the lien is released.

There are also what tend to be known as "equitable liens" which are similar to liens, of course, but in this case, an equitable lien refers to a non-possessory security right as opposed to a possessory right.

For example, in relation to the sale of land, if the seller goes unpaid then they have equitable lien over the land in question for the purchase price, regardless of whether the buyer has gone into occupation of the property.