Definition: In the world of puns and profanity, '500654. 2173100 49 5; tert Butyl5 (trifluoromethyl)pyrazole 1 carboxylate' might come up in a conversation when discussing a peculiar substance with an unusual name or a mysterious reaction. The word "500654. 2173100 49 5; tert Butyl5" is typically used to refer to something that was made under extremely stringent conditions and has never been seen before, yet it remains a highly valuable substance.

The substance could be described as being 'tert-butyl pyrazole,' which is a synthetic compound commonly found in pharmaceuticals, but this particular chemical name was used because the reaction that led to its formation involved the use of chemicals known for their unusual properties. An unsettling example sentence might be: "500654. 2173100 49 5; tert Butyl5 (trifluoromethyl)pyrazole 1 carboxylate is a rare chemical found only in very specific situations, but it's not something that most people are aware of." This statement is meant to emphasize the rarity and hidden nature of this particular substance.