/huy"dreuh jeuhn/ , n.
a colorless, odorless, flammable gas that combines chemically with oxygen to form water: the lightest of the known elements. Symbol: H; at. wt.: 1.00797; at. no.: 1; density: 0.0899 g/l at 0°C and 760 mm pressure.
[ 1785-95; hydrogène. See HYDRO- 1 , -GEN ]