Polyptoton
po-lyp-to'-ton / From Greek: poly, "many" and ptotos, "falling" or ptosis, "[grammatical] case"
Also known as: paragmenon, traductio, adnominatio, the tranlacer, many inflections
Repeating a word, but in a different form. Using a cognate of a given word in close proximity.
Examples:
With eager feeding food doth choke the feeder.
—John of Gaunt in Shakespeare's Richard II 2.1.37