Is it farther or further?
also repellant, 1640s, from Latin repellentem (nominative repelens), present participle of repellere (see repel). Originally of medicines (that reduced tumors); meaning "distasteful, disagreeable" first recorded 1797.
also repellant, 1660s, "medicine that reduces tumors," from repellent (adj.). As "substance that repels insects," 1908.
repellent re·pel·lent (rĭ-pěl'ənt)
Capable of driving off or repelling. n.
A substance used to drive off or keep away insects.