What is the meaning of the word "s.t.p."?

Definitions:

  1. A hallucinogenic drug chemically related to mescaline and amphetamine. copy to clipboard NOUN
  2. Abbreviation for 'standard temperature and pressure', used when measuring gases. copy to clipboard ABBREVIATION
    • The energy content is the total amount of energy obtained by combustion of gasoline under standard conditions, usually at STP. copy to clipboard