noun
stepson
STEP-sun/ˈstepsʌn/
A son of one's spouse from another relationship.
The mother's son becomes her new husband's stepson when they marry.

Etymology
The prefix attached to 'son' is presumed originally to have connoted loss and appeared in words for orphans. Its meaning shifted to relationship through a parent's remarriage, eventually losing the implication that a parent had died.
In context
Your stepson, John's son from his first marriage, is now the legal owner of the remaining twothirds of the estate.
More examples
- Her stepson is her husband's son from an earlier relationship.
- Both of his stepsons attend the same school.
- She proudly introduces her stepson to her coworkers.
Forms
stepson · stepsons