(agriculture) An implement having a semicircular blade and short handle, used for cutting long grass and cereal crops. / Any of the sickle-shaped middle feathers of the domestic cock.

(agriculture, transitive) To cut with a sickle. / (transitive) To deform (as with a red blood cell) into an abnormal crescent shape.

Shaped like the blade of a sickle; crescent-shaped.

(Britain) A disease characterized by sickle-shaped red blood cells.

(Australia, UK, slang) A day, or time, off work due to (supposed) illness.

(transitive) To make ill. / (intransitive) To become ill. / (transitive) To fill with disgust or abhorrence. / (sports) To lower the standing of. / (intransitive) To be filled with disgust or abhorrence.

present participle of sicken

Causing sickness or disgust. / (LGBT slang) Amazing, fantastic.

The act of making somebody sick.

Frequently ill or in poor health. / Not in good health; (somewhat) sick. / (of a plant) Characterized by poor or unhealthy growth. / Appearing ill, infirm or unhealthy; giving the appearance of illness.