SickenSICKEN, verb transitive sik'n.1. To make sick; to disease.Raise this to strength, and sicken that to death. Prior.2. To make squeamish. It sickens the stomach.3. To disgust. It sickens one to hear the fawning sycophant.4. to impair. [Not in use.]SICK'EN, verb intransitive To become sick; to fall into disease.