Definition - An inflected form that is not related to its root; instead it derives from some other unrelated word, i.e. the form doesn't resemble the base form of its grammatical paradigm.

Example -
The went in the paradigm go/goes/going/went/gone is what is called a suppletive form. Some others: good — better and person — people.

Etymology -
The word derives from the Latin suppletio, making complete.

Oxford English Dictionary -
Its first citation is from 1933:
"Athematic verbs, as well as their semantic equivalents elsewhere, seem peculiarly liable to suppletion by other verbs to furnish their aorists."
(L. H. Gray in Language IX. 84)

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