The worm represents a part of yourself that you do not like, or that you think is disgusting. Another possible dream meaning of worms is that you are dealing with self esteem issues. Perhaps you have just experienced something that lowered your self esteem.
Gastric ulcer definition, a peptic ulcer located in the stomach's inner wall, caused in part by the corrosive action of the gastric juice on the mucous membrane. See more. Dictionary.com
Definition of gas. a material that is shipped in compressed gas cylinders or acts as a gas upon release at normal temperatures and pressure, or is used or handled as a gas, whether or not in strict accordance with the definition of a compressed gas as set forth in Article 9 of the Uniform Fire Code. [SEMI S4-92].