An alternative to the title "step-dad," which is a male caregiver of a child who assumed the parental role through marriage to one of the child's original (usually biological) parents. Most commonly, a step-dad is the second husband of a child's biological mother. I live with my dad during the week and then visit my mom and bonus dad every other weekend.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.