The modern, gentle meaning of "tucked-in" represents a significant semantic softening from its Old English root. The verb 'tuck' originally carried harsh meanings related to pulling, plucking, or tormenting. Over centuries, its sense evolved to describe the physical action of drawing, folding, or pushing something into a confined or secure place, a meaning fully established by the 14th century. The phrasal verb "to tuck in" emerged, applying this action to securing bedclothes around a person or stowing away an item of clothing. As an adjective, "tucked-in" now evokes care, neatness, and comfort, completing a journey from a term of distress to one of security and order.

The term is a phrasal adjective derived from the past participle of the verb phrase 'to tuck in'. 'Tuck' originates from Middle English tukken, touken, from Old English tūcian ("to torment, to ill-treat") and likely from Proto-Germanic. The preposition 'in' is from Old English in, from Proto-Germanic in.