What is "lamb lettuce"

Lamb \Lamb\, n. [AS. lamb; akin to D. & Dan. lam, G. & Sw. lamm, OS., Goth., & Icel. lamb.]

1. (Zo["o]l.) The young of the sheep.

2. Any person who is as innocent or gentle as a lamb.

3. A simple, unsophisticated person; in the cant of the Stock Exchange, one who ignorantly speculates and is victimized.

   Lamb of God, The Lamb (Script.), the Jesus Christ, in allusion to the paschal lamb.

   The twelve apostles of the Lamb.
   --Rev. xxi. 1

4. Behold the Lamb of God, which taketh away the sin of the world. --John i. 29. Lamb's lettuce (Bot.), an annual plant with small obovate leaves ( Valerianella olitoria), often used as a salad; corn salad. [Written also lamb lettuce.] Lamb's tongue, a carpenter's plane with a deep narrow bit, for making curved grooves. --Knight. Lamb's wool.

   1. The wool of a lamb.

   2. Ale mixed with the pulp of roasted apples; -- probably from the resemblance of the pulp of roasted apples to lamb's wool. [Obs.]
      --Goldsmith.