The words “flammable” and “inflammable” mean the same thing: “easily set on fire”. Why is this?
In English, the in- prefix is often used to reverse the meaning of an adjective. Thus inactive is the opposite of active and inelegant is the opposite of elegant. So why isn’t inflammable the opposite of flammable?
The reason is that the in of inflammable is not the prefix meaning “not”. Inflammable derives from the Latin in meaning into and flamma, “a flame”. Flammable derives simply from flamma. Inflammable is thus very close to the word enflame, which has the same origin.
In practice, it can be confusing having two words that sound as if they could be opposites but which actually mean the same thing. It could even be dangerous, if “inflammable” were taken to mean “not flammable”. The Compact Oxford English Dictionary recognizes this and recommends using “flammable” at all times :
The words flammable and inflammable have the same meaning. It is, however, safer to use flammable to avoid ambiguity, as the in- prefix of inflammable can give the impression that the word means ‘non-flammable’.”
As this quotation makes clear, the opposite of flammable is not inflammable but “non-flammable” or simply “not flammable”.
16 thoughts on “Don’t Be Burnt By “Inflammable””
Great and informative post Simon. Thanks, in fact for a long time I used to get confused about the meaning of inexpensive, I thought if inflammable is highly flammable, then inexpensive would be highly expensive. Somewhat like invaluable.
Once while reading an article, I saw the word used meaning, cheap, and I decided to look it up, and suddenly I discovered, it was quite different.
Today’s comic strip “Frank and Ernest” is about the same topic!
Please fix your periods.
My pet peeve. It looks bad for a writing site to make these mistakes.
I remember the definition by remembering the following:
Inflammable, as in inflame
Inflame (trans. verb): to set on fire
Inflame (intrans. verb): to burst into flame.
(Enflame is an alternative spelling for inflame.)
Inflammable is most closely related to the intransitive verb, i.e., capable of bursting into flame.
Now, I wonder if we have other words like inflammable. Hmm.
Shouldn’t this have read “burned”, not “burnt”?
Thank you very much Simon Kewin for your great information and explanation, without which I would have stayed confused forever. Keep up!
Read this post and remembered how i nearly set the house on fire. I used to see Highly Inflammable on one of the deodorants of my sister. I was about 10 years old then and thought it meant I can put off fire with it. I lit a candle and sprayed the deodorant on it. I burst into flames and I got so scared. Luckily nothing was damaged except for the bottle. I learnt then that inflammable meant flammable. Thanks Simon for this information. I hope no one repeats the mistake again. 🙂
Now i can understand the different between them.
you explanation is good
I have reached the age of 65, teach English for a living, written millions of words and had many of them published and have never realised until I read this that I had misunderstood the meaning of inflammable all my life!! What does this mean? That I am illiterate, a bad teacher or ill-educated? No, it means I have simply had no reason to use it or be interested in the meaning further than a casual or passing mention that lasted for the duration of a death throe of a synaps. Still, I’m glad I know – but I still don’t quite believe – that inflammable doesn’t mean ‘can’t set on fire’!
As to periods (full stops) inside quotation marks, it’s a fair point that in US English the standard is to always put the period inside. But in British English this isn’t the case. Here, the period only goes there if the quotation logically contains a full-stop. If you’re ending a sentence with a phrase that doesn’t logically contain a period, then the period goes outside the quotation marks.
Perhaps we need another post to fully explore these differences between the different variants of English.
Aye, British punctuation conventions. Simon did it right. That period goes outside (I wish this were true in American conventions).
See “The Brits Got It Right: Punctuation with quotations” ( for more about how the British and American conventions differ.
Regarding inflammable deodorant: That’s funny (though dangerous). What a great way to learn about “inflammable”. [nod to Simon]
I have been thinking what is the proper use of Go and Come. To me, when I hear the word go I will think of the word THERE and come will be HERE. I always say <>. Yet, I keep hearing from the American movies the use of come instead of go. For example, they will say <>.
Can anyone here help explain to me. What is the best choice to use in my situation, GO or Come?
Your contribution would be highly appreciated.
But in British English this isn’t the case. Here, the period only goes there if the quotation logically contains a full-stop.
That must be a very modern rule, if it’s true at all — I’ve heard it reported several times, but checking by now probably hundreds of British and British-published books, I have yet to find a single example of this “rule” used by professional publishers. (But I admit to not having looked carefully at any book published this century…)
Excellent explanation, Simon. I do appreciate you clearing up the “will burn” issue. As comedian George Carlin quipped “Either the [bleep] stuff flams or it don’t flam!”
Very nice and helpful information has been given
in this article. I like the way you explain the
things. Keep posting. Thanks.
Great post Simon. It was good to see that others have pondered this antagonism too.
@Laya: “Somewhat like invaluable.”
-But for invaluable in- really does mean not. As in “This is beyond any price you can name, I am NOT ABLE to set a VALUE for it.” 😉
As for the “quoting and punctuation” discussed:
@Peter, this rule does not need to be written (even if it may be), as it is a priori and only logical. Periods serve much the same purpose as quotation marks. To have a quote within a sentence makes just as much sense as having a sentence within a quote.
I hope someone enjoys my contribution as much as I enjoyed posting it. And Simon: I’m sorry for taking this thread further off its topic. 😉