ETYM Old Eng. sikel, as. sicol; akin to Dutch sikkel, German sichel, Old High Germ. sihhila, Dan. segel, segl, Latin secula, from secare to cut; or perhaps from Latin secula. Related to Saw a cutting instrument.
An implement for cutting grass or crops; has a curved blade and a short handle; SYN. reaping hook, reap hook.
Harvesting tool of ancient origin characterized by a curving blade with serrated cutting edge and short wooden handle. It was widely used in the Middle East and Europe for cutting wheat, barley, and oats from about 10,000 bc to the 19th century.

Having the form of a sickle blade; having a curve similar to that of a sickle blade

1. To mow or reap with a sickle
2. To change (a red blood cell) into a sickle cell
3. To change into a sickle cell