The words "flammable" and "inflammable" might sound like they should mean opposite things, but surprisingly, they both describe substances that are easily set on fire. This often causes confusion because the prefix "in-" in English typically indicates negation or the opposite, as seen in pairs like "independent" vs. "dependent" or "inconclusive" vs. "conclusive." However, in the case of "inflammable," the prefix comes from the Latin word "inflammare," which means "to inflame."
The term "inflammable" came into English around the early 1600s and was derived directly from Latin. It became the standard term used to describe materials that can ignite quickly. Much later, due to the potential for misunderstanding (with the assumption that "inflammable" meant "not flammable"), safety experts and standards organizations pushed for a clearer term. Thus, "flammable" began to be used widely to avert dangerous misunderstandings.
By the mid-20th century, "flammable" was adopted in safety labels to ensure that people understood that substances labeled as such are indeed capable of ignition. This move was primarily guided by the intention to enhance clarity and safety, especially in industrial and consumer contexts where the risk of fire is a serious danger, and misinterpretation could lead to catastrophic results.
Today, "flammable" is more commonly used in product labels, safety warnings, and technical documents to avoid confusion. While "inflammable" is still correct and appears in dictionaries, its use in safety communications is discouraged to prevent misunderstanding. Both terms, however, technically serve the same purpose of indicating that a material can catch fire easily; therefore, regardless of the term used, safety precautions should be equally stringent.
