Suppletion (definition)

in morphology this is when an alteration completely changes a word. These changes cannot be explained by rules because the new forms of the word have different roots. An example of this would be “went” and “go.”

References

Crystal, David, and David Crystal. The Penguin Dictionary of Language. London: Penguin, 1999.

Matthews, P. H. The Concise Oxford Dictionary of Linguistics. Oxford: Oxford University Press, 1997.