Canadian Law Dictionary.
A legal procedure whereby you can seek reimbursement from another who benefitted from your action or property without legal justification. There are said to be three conditions which must be met before you can get a court to force reimbursement based on "unjust enrichment": an actual enrichment or benefit to the defendant, a corresponding deprivation to the plaintiff, and the absence of a legal reason for the defendant's enrichment.
From ancient Roman law (and now a part of many civil law systems), "usufruct" means the rights to the product of another's property. For example, a farmer may give a right of "usufruct"of his land to a neighbor, thus enabling that neighbor to sow and reap the harvest of that land.
Excessive or illegal interest rates. In Canada it is interest greater than 60% per annum (Section 347 of the Criminal Code).