What is a figure by which a word is repeated in different forms, cases, numbers, genders, etc., as in Tennyson's line, -- "My own heart's heart, and ownest own, farewell." called?

polyptoton — A figure by which a word is repeated in different forms, cases, numbers, genders, etc., as in Tennyson's line, -- "My own heart's heart, and ownest own, farewell.". (Webster's 1913.)

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