Calentures refer to the feverish delirium experienced by sailors during long voyages. It is a term that is rarely used in modern times. However, we can discuss its antonyms, which are words that have the opposite meaning. Some antonyms for calentures could include serenity, calmness, coolness, level-headedness, and lucidity. These words reflect the opposite state of mind that sailors experienced during their feverish dreams while at sea. Ultimately, the use of antonyms is an effective way to explore various meanings and nuances of a word while helping learners improve their vocabulary and language skills.