Alkenes are a class of unsaturated hydrocarbons that contain at least one double bond between carbon atoms. There are several synonyms used to refer to alkenes, such as olefins, ethylenes, and acetylenes, depending on the chemical structure of the compound. Olefins generally refer to aliphatic alkenes, while ethylenes are used to describe the simplest member of the alkene family, ethylene or ethene. On the other hand, acetylenes are a class of unsaturated hydrocarbons that contain at least one triple bond and are not technically alkenes. These synonyms are often used interchangeably in scientific literature and discussions about organic chemistry.