The Collaborative International Dictionary of English v.0.48:

Duckmeat \Duck"meat`\, Duck's-meat \Duck's"-meat`\, n. (Bot.)
   Duckweed.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Duckweed \Duck"weed`\, n. (Bot.)
   A genus (Lemna) of small plants, seen floating in great
   quantity on the surface of stagnant pools fresh water, and
   supposed to furnish food for ducks; -- called also
   duckmeat.
   [1913 Webster]