Middle English word stepchild comes from Old English stēop-, Old English ċild, Old English stēopċild, and later Old English steopcild (Stepchild.)

Detailed word origin of stepchild

Dictionary entry	Language	Definition
stēop-	Old English (ang)
ċild	Old English (ang)
stēopċild	Old English (ang)
steopcild	Old English (ang)	Stepchild.
stepchyld	Middle English (enm)

Words with the same origin as stepchild