sickled

Sickled is an adjective meaning shaped like a sickle, i.e., curved or crescent-shaped. It is used across disciplines to describe objects with a curved profile reminiscent of the farming tool, such as plant leaves or blades, and in medical contexts to describe red blood cells that have assumed a crescent form. The term can also function as the past tense of the verb to sickle, meaning to cut with a sickle or to harvest.

In hematology, the phrase "sickled cells" refers to red blood cells that become crescent- or sickle-shaped under low oxygen tension due to polymerization of hemoglobin S. Sickling reduces red cell deformability and can cause vaso-occlusion, hemolysis, and pain crises in sickle cell disease. The term is descriptive and commonly used in microscope smear descriptions and clinical notes, though more precise language such as "crescent-shaped" is also used.

In botany and plant morphology, sickled describes leaves or other organs with a strongly curved or hooked outline. The usage emphasizes shape and is not tied to a specific taxon.

Etymology: sickled derives from sickle, from Old English sicol or sicol, related to German sickel, and formed with the regular English past participle suffix -ed. The medical usage arises from the resemblance of deformed cells to the curved blade of a sickle.