The word "barbiturate" refers to a class of drugs that induce sleep, calm nerves, or relieve anxiety. Antonyms for this word could include stimulants, such as caffeine or amphetamines, which increase alertness and energy levels. Other antonyms might be substances that induce excitement or euphoria, like hallucinogens or opioids. Another possible antonym for barbiturates might be medications that treat depression or mood disorders, such as selective serotonin reuptake inhibitors (SSRIs), which work by increasing the levels of certain neurotransmitters in the brain. Ultimately, the choice of antonyms will depend on the specific context and intended meaning of the word "barbiturate" in a particular sentence or conversation.