Gas giants are a type of planet that are composed mainly of hydrogen and helium. They are the largest planets in our solar system and are sometimes referred to as 'Jovian' planets. The four crossword solutions for the term 'gas giant' are Exxon, AMOCO, Mobil, and Enron. Exxon is an American multinational oil and gas corporation headquartered in Texas. AMOCO is an American oil and gas company that was acquired by BP in 1998. Mobil is an American oil and gas company that merged with Exxon in 1999. Enron is an American energy, commodities, and services company that declared bankruptcy in 2001.