In a state of dreaming or in a dreamlike condition; lost in thought or reverie.
From 'a-' (in a state of) + 'dream.' An archaic or poetic formation meaning 'in a dream' or 'dreaming,' commonly used in older English literature.
Poets loved 'adream' because it's more evocative than just saying 'dreaming'—it suggests being caught in a dreamlike state, suspended between reality and imagination, and you'll find it in Romantic poetry.
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