the word 'tomato' entered english in the early 17th century from the spanish word 'tomate'. this, in turn, was borrowed from the nahuatl (the language of the aztecs) word 'tomatl', which simply meant "the swelling fruit". the journey of the word reflects the journey of the plant itself, which was domesticated in mesoamerica and introduced to europe following the spanish colonization of the americas. the initial resistance in europe to eating the fruit, due to its relation to the nightshade family, contrasts with its eventual global culinary dominance. its name, a direct phonetic borrowing, carries the history of this transatlantic exchange.

the word 'tomato' is a simplex loanword. it does not contain separable morphemes within its modern english spelling.