stepgrandson

step- +‎ grandson

stepgrandson (plural stepgrandsons)

1. The grandson of one's stepgrandfather's wife or stepgrandmother's husband from previous marriage, or the stepson of one's child.
   • 2009 January 23, Susan Dominus, “Coming Up Short as a Role Model for the Mommy Track”, in New York Times‎:

     The son of an out-of-work contractor can hope for a crack someday at a Senate seat, knowing that the stepgrandson of a woman who lives in a metal-roofed shack is moving into the White House.

• stepgrandchild
• stepgranddaughter
• stepgrandfather
• stepgrandmother
• stepgrandparent