Every so often, somebody will email me about words and meanings. Sometimes it’s a suggestion for words that they’ve seen misused (most recently, invasive when evasive was meant), sometimes it’s a question. Recently, my friend Sara Mallory sent a Facebook message asking about today’s words. What’s the difference between them?
flammable
Capable of being set on fire; combustible.
inflammable
Capable of being set on fire; combustible.
This seems odd, doesn’t it? Two words that are almost the same and mean exactly the same thing? Why? Especially since there are so many words where the prefix in- means “not,” such as indistinct, inactive, incongruous, etc.
The answer is evolution. Specifically, the evolution of language. In Latin, there were two similar prefixes, in- and im-; im- meant “not” and in- meant “in.” A lot of words using these prefixes have survived to the present day, like inspiration and imprecise, but over time, a lot of im- words morphed into in- or un- words, like incompetent and unbreakable. The result is that we have a lot of in- words that mean in- and a lot that mean un-, which makes for a confusing prefix.
Inflammable first came to English around 1600, from the Latin inflammabilis, from inflammare, in + flame, meaning something that burns.
In the 1920s, government officials realized that because of the confusing quirks of language described here, people might erroneously believe that inflammable means “fireproof,” so they asked manufacturers and organizations to use the shortened word flammable in order to avoid possibly fatal confusion.
No matter which one you use, it means “it burns real good.”
“Flammable means inflammable? What a country!” https://www.youtube.com/watch?v=Q8mD2hsxrhQ