substĭtūtĭo, ōnis, f. [substituo, II.].
I In gen., a putting in the place of another , substitution , Arn. 3, p. 104.—
II In partic., in jurid. lang., the appointment of a second or alternate heir , Gai. Inst. 2, § 174 sq.; Dig. 28, tit. 6.