[ma¦thäk·sē¦eth·əl¦mər·kyə·rē ′klȯr‚īd] (organic chemistry) CH3OCH2CH2HgCl A white, crystalline compound with a melting point of 65°C; used as a fungicide in diseases of sugarcane, pineapples, seed potatoes, and flower bulbs, and as seed dressings for cereals, legumes, and root crops. Abbreviated MEMC.