The Collaborative International Dictionary of English v.0.48:

Sickle \Sic"kle\, n. [OE. sikel, AS. sicol; akin to D. sikkel,
   G. sichel, OHG. sihhila, Dan. segel, segl, L. secula, fr.
   secare to cut; or perhaps from L. secula. See Saw a cutting
   instrument.]
   1. A reaping instrument consisting of a steel blade curved
      into the form of a hook, and having a handle fitted on a
      tang. The sickle has one side of the blade notched, so as
      always to sharpen with a serrated edge. Cf. Reaping
      hook, under Reap.
      [1913 Webster]

            When corn has once felt the sickle, it has no more
            benefit from the sunshine.            --Shak.
      [1913 Webster]

   2. (Astron.) A group of stars in the constellation Leo. See
      Illust. of Leo.
      [1913 Webster]

   Sickle pod (Bot.), a kind of rock cress (Arabis
      Canadensis) having very long curved pods.
      [1913 Webster]

WordNet (r) 3.0 (2006):

sickle
    n 1: an edge tool for cutting grass or crops; has a curved blade
         and a short handle [syn: sickle, reaping hook, reap
         hook]

Easton's 1897 Bible Dictionary:

Sickle
   of the Egyptians resembled that in modern use. The ears of corn
   were cut with it near the top of the straw. There was also a
   sickle used for warlike purposes, more correctly, however,
   called a pruning-hook (Deut. 16:9; Jer. 50:16, marg., "scythe;"
   Joel 3:13; Mark 4:29).