The word 'sweet-potato' is a straightforward compound formed in English. The first element, 'sweet', is a native English word of Germanic origin, ultimately from the Proto-Indo-European root swād- ('sweet, pleasant'). The second element, 'potato', has a more complex journey, entering English via Spanish from the Taino (Caribbean) word 'batata'. The compound name 'sweet potato' was coined to distinguish this plant, with its sugary, orange-fleshed tuber, from the common (white) potato, to which it is botanically unrelated. The term thus logically describes the tuber's characteristic taste.

Structure: sweet (adjective) + potato (noun) sweet: From Old English swēte, meaning 'pleasing to the senses, having a pleasant taste'. It functions as an adjective modifying the following noun. potato: From Spanish patata, itself from Taino batata. It functions as the core noun, naming the plant or tuber.