rētae

ārum, f.
I. trees standing on the bank or in the bed of a stream, acc. to Gabius ap. Gell. 11, 17, 4.— From this is said to come the verb retare, to clear, free from obstructions, in an old edict: flumina retanda; v. Gell. l. l.
Lewis & Short
A Latin Dictionary, 1879
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