Usucaption (Latin usucapio) (in U.S. and U.K. known as acquisitive prescription) is a concept found in civil law systems and has its origin in the Roman law of property.

Usucaption is a method by which ownership of property (i.e. title to the property) can be gained by possession of it beyond the lapse of a certain period of time (acquiescence). While usucaption has been compared with adverse possession (that is, squatting), the true effect of usucaption is to remedy defects in title.