[¦sim dī¦klȯr·ō′eth·ə‚lēn] (organic chemistry) CHClCHCl Colorless, toxic liquid with pleasant aroma, boiling at 59°C; decomposes in light, air, and moisture; soluble in organic solvents, insoluble in water; exists in cis and trans forms; used as solvent, in medicine, and for chemical synthesis.