Definition of the word vapour

The word "vapor" or "vapour" (depending on the spelling variation used) has its origins in the Middle English language, which was spoken during the 14th and 15th centuries. The root of the word can be traced back to the Old French word "vapor," which itself originated from the Latin term "vapor" meaning "exhalation," "steam," or "vapour." In Latin, the verb "vapor" meant "to breathe out," and the noun referred to the resulting mist or steam that emerged from a liquid or solid substance. This meaning carried over into Middle English, where "vapour" was used to describe the same phenomena. The word was commonly used to refer to the mist or fog that arose from swamps, rivers, or other damp places, as well as the steam that rose from cooking pots or other sources. Over time, the meaning of "vapor" and "vapour" has evolved to encompass other forms of gas or mist, including those that are not necessarily the result of exhalation or evaporation. In scientific contexts, "vapour" is used to describe a substance that is in a gaseous state at atmospheric pressures, whereas "gas" is used to describe a substance that is in a gaseous state at pressures other than atmospheric. The different spellings of "vapor" and "vapour" can be attributed to the varying spellings of English words over the centuries. In Old English, the word for "vapor" was "æpwura," a compound of "æg" (meaning "egg" or "surrounding") and "wyrwan" (meaning "thrown"). This word eventually evolved into "vapour" in Middle English, but in Early Modern English, the spelling "vapor" began to emerge due to influence from other languages, such as French and Latin. The two spellings remain in use today, although "vapour" is more commonly used in British English, whereas "vapor" is more commonly used in American English.