Visual Energy Terminology Add to favorites tutorial Gas – (1) A non-solid, non-liquid (as hydrogen or air) substance that has no fixed shape and tends to expand without limit. (6801) Page Views Pages: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35