The phrase "hydrogen escape" refers to the process in which hydrogen gas, found in an atmosphere or a body of water, slowly escapes or leaves its original location. Full definition
Then, sunlight split the water molecules, letting hydrogen escape into space. (sciencemag.org)
But he says the argument would be more persuasive if it explained why the crust would have absorbed the excess oxygen produced by hydrogen escape. (sciencemag.org)
The rate of loss varied dramatically overall, with 10 times more hydrogen escaping at the maximum. (sciencedaily.com)