This is part of the dif­fer­ence between series.

I’ve heard some peo­ple con­fus­ing the words flam­ma­ble and inflam­ma­ble. Here’s the dif­fer­ence between the two.

Actu­al­ly, there’s no dif­fer­ence; inflam­ma­ble and flam­ma­ble are syn­ony­mous.

The assump­tion that they have oppo­site mean­ings may derive from the fact that inflam­ma­ble has an in- pre­fix, which typ­i­cal­ly has a neg­a­tive con­no­ta­tion:

  • invis­i­ble
  • incapa­ble
  • inexpen­sive

How­ev­er, the root of inflam­ma­ble is inflame (some­times spelled enflame). Inflame has mul­ti­ple mean­ings today, a pop­u­lar one being to pro­voke to anger. Anoth­er mean­ing, how­ev­er, is to set on fire. Inflame comes from the Latin inflam­mare (flam­mare, “to catch fire”; in-, “to cause to”).

Oth­er Eng­lish words using the in- pre­fix that don’t have a neg­a­tive mean­ing include:

  • inscribe
  • inquire
  • impress
  • immi­grate

Inflam­ma­ble has been around for 200 years longer than flam­ma­ble, so arguably, it’s more cor­rect. That being said, a lot of peo­ple think it’s incor­rect, so if you use it, tread care­ful­ly.

Which words do you con­fuse? Let me know in the com­ments below.

Inter­est­ed in more gram­mar tips like this? Sign up for our free week­ly newslet­ter.

About Kim Siever

I am a copy­writer and copy­ed­i­tor. I blog on writ­ing tips most­ly, but I some­times throw in my thoughts about run­ning a small busi­ness.

Fol­low me on Twit­ter at @hotpepper.

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