Definition of Encroachment
An illegal intrusion in a highway or navigable river, with or without obstruction. Hartford Elec. Light Co. v. Water Resources Commission, 162 Conn. 89, 291 A.2d 721, 730. An encroachment upon a street or highway is a fixture, such as a wall or fence, which illegally intrudes into, invades the highway, or incloses a portion of it, diminishing its width or area, but without closing it to public travel.
In the law of easements, where the owner of an easement alters the dominant tenement, so as to impose an additional restriction or burden on the servient tenement, he is said to commit an encroachment.
That's the definition of Encroachment in Black's Law Dictionary 6th Edition. Courtesy of Cekhukum.com.