1 However, discomfort in the abdomen for any reason also may cause belching. 2  Therefore, belching does not always indicate the presence of excessive gas in the stomach. 3  Bloating is the subjective feeling that the abdomen is full but does not necessarily mean that the abdomen is enlarged.
caustic(Noun) Any substance or means which, applied to animal or other organic tissue, burns, corrodes, or destroys it by chemical action; an escharotic. caustic(Noun) The envelope of reflected or refracted rays of light for a given surface or object.
The term caustic can also mean corrosive.. This type of brake fluid can be corrosive to some paints, chromes, and plastics. It also can cause irritation when exposed to skin, and is toxic if ingested. I suspect this is why brake fluid is labeled as caustic. Regarding your question about pH: it doesn't apply. pH is a measure of the H+ ions in an aqueous (water) solution. The lower the pH, the greater the content of H+ ions in the water, and the more acidic it is.