One who has committed trespass; one who unlawfully enters or intrudes upon another’s land, or unlawfully and forcibly takes another’s personal property. Joint trespassers. Two or more who unite In committing a trespass. Trespasser ab initio. Trespasser from the beginning. A term applied to a tort-feasor whose acts relate back so as to make a previous act, at the time innocent, unlawful; as, if he enter peaceably, and subsequently commit a breach of the peace, his entry is considered a trespass.