Step-. [AS. steop-; akin to OFries. stiap-, stiep-, D. & G. stief-, OHG. stiuf-, Icel. stjp-, Sw. styf-, and to AS. ast�xc7;pan, asteopan, to deprive, bereave, as children of their parents, OHG. stiufen.]
A prefix used before father, mother, brother, sister, son, daughter, child, etc., to indicate that the person thus spoken of is not a blood relative, but is a relative by the marriage of a parent; as, a stepmother to X is the wife of the father of X, married by him after the death of the mother of X. See Stepchild, Stepdaughter, Stepson, etc.
© Webster 1913.