c. 1200, "to become ill," from sick (adj.) + -en (1). Transitive sense of "to make sick" is recorded from 1610s. Related: Sickened; sickening. The earlier verb was simply sick (Old English seocan) "to be ill, fall ill."
siccative
sice
Sicily
sick
sick-bay
sicken
sickening
sickish
sickle
sickly
sickness