glycolaldehyde

noun
gly·​col·​al·​de·​hyde | \ ˌglī-(ˌ)kȯl-ˈal-də-ˌhīd, -(ˌ)kōl- How to pronounce glycolaldehyde (audio) \

Medical Definition of glycolaldehyde

: a compound that exists in solution as the diose C2H4O2 but that exists in the anhydrous state only as the crystalline dimer C4H8O4