[mass noun]a colourless, odourless, highly flammable gas, the chemical element of atomic number 1(Symbol: H) (化学元素)氢(符号: H)
Hydrogen is the lightest of the chemical elements and has the simplest atomic structure, a single electron orbiting a nucleus consisting of a single proton. It is by far the commonest element in the universe, although not on the earth, where it occurs chiefly combined with oxygen as water
派生 hydrogenous [-ˈdrɒdʒɪnəs] adjective 语源
late 18th cent.: coined in French from Greek hudro- 'water' + -genēs (see -gen)