From Longman Dictionary of Contemporary Englishsennasen‧na /ˈsenə/ noun [uncountable] HBPMDa tropical plant with a fruit that is often used to make a medicine to help your bowels work
Examples from the Corpus
senna• Dieters are particularly vulnerable to the side effects of laxatives like senna.• For instance, in 1666 he was granted a licence for the cultivation of senna in the plantations.• People who use senna can also become addicted to its laxative effects.• We must be certain we like the looks of a plant such as wild senna, .Origin senna (1500-1600) Modern Latin Arabic sana 