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English and German: topographic name for someone who lived by the sea-shore or beside a lake, from Middle English see ‘sea’, ‘lake’ (Old English s?), Middle High German se. Alternatively, the English name may denote someone who lived by a watercourse, from an Old English seoh ‘watercourse’, ‘drain’.
Dictionary of American Family Names, Oxford University Press, ISBN 0-19-508137-4