In Roman law. An increase or addition; that which lies next to a thing, and is supplementary and necessary to the principal thing; that which arises or is produced from the principal thing. Calvin. Lex. Jurid. One of the modes of acquiring property, being the extension of ownership over that which grows from, or is united to, an article which one already possesses. Mather v. Chapman, 40 Conn. 382, 397, 16 Am. Rep. 46.