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

(Canada, US) A disease characterized by sickle-shaped red blood cells.

(sports, billiards, snooker, pool) A sidespin of the cue ball which makes it bounce off the cush, or off another ball, at a shallower angle than normal.

Moving or turning back and forth.

(ornithology) A large white crane, Grus leucogeranus, which breeds in Arctic Russia and western Siberia.

(archaic) Epilepsy.

Alternative spelling of sidefoot

Used other than figuratively or idiomatically: be sick. / (informal) To vomit.

Moving horizontally, from one side to another and back.

A child, conceived by selected IVF treatment, so as to have compatible tissue that could be used to treat an existing sick brother or sister