| rill | 1. A very small brook; a streamlet. 2. <astronomy> See Rille. Origin: Cf. LG. Rille a small channel or brook, a furrow, a chamfer, OE. Rigol a small brook, F. Rigole a trench or furrow for water, W. Rhill a row, rhigol a little ditch. Source: Websters Dictionary (01 Mar 1998) |
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| rille | <astronomy> One of certain narrow, crooked valleys seen, by aid of the telescope, on the surface of the moon. Origin: G. Rille a furrow. Source: Websters Dictionary (01 Mar 1998) |