An Etymological Dictionary of Astronomy and Astrophysics

prefix meaning “bad, ill, abnormal.”

Etymology (EN): From Gk. dys- “bad, hard, unlucky,” cognate with O.Pers. duš-, Av. duž- (see below), Skt. dus- “bad, wrong, difficult, un-, -less,” PIE *dus- “bad, ill.”

Etymology (PE): Doš-, dož- “bad, ill, abnormal,” from Mid.Pers. duž-, duš-,
O.Pers. duš- (dušiyâr- “bad year, famine”), Av. duž-, duš- “bad” (duž-mainnyav- “evil-minded, enemy,” Mod.Pers. došman “enemy”); PIE *dus-, as above.