word ?????? (haplóos) is "single", from ?- (ha-, "one, same"). ??????? (diplóos) means "duplex" or "two-fold". Diploid therefore means "duplex-shaped" (compare "humanoid", "human-shaped").

Polish-German botanist Eduard Strasburger coined the terms haploid and diploid in 1905. Some authors suggest that Strasburger based the terms on August Weismann's conception of the id (or germ plasm), hence haplo-id and diplo-id.