In a state of death or lifelessness; completely dead (archaic or poetic usage).
From Old English 'a-' (prefix meaning 'in a state of') combined with 'dead,' though this formation is archaic and rarely appears in modern usage.
This old prefix 'a-' (meaning 'in a state of') appears in some surviving English words like 'ablaze' and 'alight,' showing how Old English used prefixes differently than modern English does.
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