The terms yam and sweet potato are often confused. We will examine the definitions of the words yam and sweet potato, where they came from and some examples of their use in sentences.
A yam is a starchy tuberous crop from Africa or Asia with a rough, brownish exterior and a white or yellowish interior. There is little carotene in a yam. It is a member of the Dioscorea genus, and usually comes from Caribbean countries. Yams may be eaten in place of rice, potatoes or bread. The word yam is derived from either the African word nyami meaning to eat, or the Spanish word igname.
A sweet potato is also a starchy tuberous crop from South or Central America with smooth orangish, reddish or brownish skin and red or orange flesh. It is a member of the Convolvulaceae family, which includes the morning glory flower. When African slaves encountered the sweet potato they called it a yam, as it reminded them of the tubers from their homeland. To this day, the terms yam and sweet potato are used interchangeably in the United States, though they are properly identified as two different crops. The sweet potato was originally simply called a potato, from the Haitian Carib word batata.
Examples
But since we’re friends, he must also know I once called him “a bloviating yam.” (The Washington Post)
Almost everything yam-like that you can find in a grocery store is actually going to be a sweet potato — even the ones with red skins. (The St. Louis Post-Dispatch)
The celebration of New Yam festival by Ndigbo is a cultural identity through which the people continue their quest for unity, peace and togetherness. (The Nation)