The word 'stepdaughter' is a compound formed from two Old English elements. The prefix 'step-' originates from the Old English 'stēop-', which carried the specific meaning of orphaned or bereaved, later evolving to denote relationships created by the remarriage of a parent. The core noun 'daughter' comes from the Old English 'dohtor', a term with deep Proto-Indo-European roots (dʰugh₂tḗr) signifying a female child. The compound thus logically constructs the meaning of a female child who becomes one's daughter through the new marital union of a parent, rather than by biological descent.

Structure: step (related by remarriage) + daughter (female child) - step: From Old English 'stēop-', meaning "related by remarriage of a parent," functioning as a prefix denoting a relationship through marriage. - daughter: From Old English 'dohtor', meaning "female child," functioning as the core noun.