Properly the name of an edible tuber of plants of the genus Dioscorea, ‘yam’ is often used in a general sense to embrace other tropical root crops such as sweet potato, taro, oca, etc. The wider usage is an inconvenience; all the more so since the genus Dioscorea itself comprises scores of species which are often difficult to distinguish from each other. However, one must not complain. The origin of the word ‘yam’ was such that its meaning had to be elastic. The story goes that Portuguese slave traders, watching Africans digging up some roots, asked what they were called. Failing to understand the question aright, the Africans replied that it was ‘something to eat’, nyami in Guinea. This became inhame in Portuguese and then igname in French, and yam in English.