The crossword solutions for the term 'Helium or Oxygen' are GAS, which stands for a group of chemical elements that are in a gaseous state at room temperature and pressure. Helium and Oxygen are two of the most common gases found in Earth's atmosphere. Helium is a colorless, odorless, and tasteless GAS that is the second most abundant element in the universe. Oxygen is a colorless, odorless, and tasteless GAS that is the most abundant element in the universe and makes up about 21% of the Earth's atmosphere. Both gases are essential for life on Earth.