Three Commonly Confused In- Words: Infamous, Invaluable, and Inflammable

blog home

Often, when a word starts with in-, we can assume that it means the opposite of the same word without the in-.

Invisible’, for example, means ‘not visible’, or ‘intolerant’ means ‘not tolerant’.

This is because one of the translations of the Latin prefix in- is ‘not’.

Today, we’re going to look at three exceptions to this rule. Scroll down to make sure you’re using the following in- words correctly!

  1. Famous vs. Infamous

    If someone isn’t famous, it doesn’t mean that they’re infamous. Let’s take a look at the Spellzone dictionary definitions of each word:

    Famous: widely known and esteemed

    Infamous: known widely and usually unfavourably. In short: if someone is famous for a negative reason, they are infamous.

    Example sentences:
    • The pop star was so famous that he could hardly go anywhere without seeing his own face on a billboard.
    • The old man who lives at the end of our road is infamous for his bad temper.
  2. Valuable vs. Invaluable

    Again, if something or someone is invaluable, that doesn’t mean that it/they have no value. Here are the Spellzone dictionary definitions of these two words:

    Valuable: - something of value - having great material or monetary value especially for use or exchange - having worth, merit or value

    Invaluable: having incalculable monetary, intellectual, or spiritual worth

    So if something is ‘invaluable’ it is usually of the type of value that cannot be counted.

    Example sentences:
    • My gold necklace is extremely valuable – I’m scared of wearing it in case I lose it.
    • The help she gave him before his spelling test was invaluable – he passed with full marks.

    The difference between the words ‘less’ and ‘fewer’ is also to do with whether the thing being talked about can be counted or not – click here for more information on using these words.

  3. Flammable vs. Inflammable

    Unlike the two previous examples, where there is a slight difference in the definitions of the two words, ‘flammable’ and ‘inflammable’ both mean exactly the same thing. The Spellzone dictionary definition of both words is as follows:

    Flammable: easily ignited

    Inflammable: easily ignited

    The word ‘inflammable’ predates ‘flammable’, with the former first coming into use in the fifteenth century, and the latter in the nineteenth century. It is entirely possible that use of the word ‘flammable’ became popular due to people assuming that ‘inflammable’ meant ‘not flammable’.

    Example sentences:
    • Be careful when filling your car – petrol is highly flammable.
    • They threw inflammable materials onto the bonfire to keep it lit.

If you’re interested in how prefixes change the meanings of words, you can find out more here:

Are there any words that you’re not quite sure how to use? Let us know and we’ll feature them on our blog. You can contact us on Facebook or Twitter.


22 Aug 2014
blog home

One of the students has put in a huge amount of effort in completing Spellzone at least 3 times a week since his arrival with us in January. Looking at his scores after the latest GL testing, his standardised score has risen from 99 to 131. This is a truly phenomenal result. I just wanted to share the best result I have ever seen.

Terrie Penrose-Toms, Casterton College