Word formation is a very useful and interesting field to study. Today we will talk about adjectives. In fact, English nouns and adjectives have the biggest amount of suffixes and prefixes! Remember that adjectives can be simple “big, beautiful, unnecessary, etc.” and compound “light-green, well-done, worldwide, etc.”. We will talk about simple adjectives, formed by adding prefixes. Here we go!

We can form another adjective by adding to an adjective a prefix, like “possible + im = impossible”. Here, as you see, the adjective “possible” does not change itself. Unless while forming an adjective with a suffix we add a suffix to a noun/verb and the noun/verb can be changed a bit, like “rely - reliable, etc.”. With prefixes it does not happen, we take an adjective and add a prefix at the beginning. The majority of the prefixes in this case will have the same meaning: they will add the meaning of negation, the lack of some feature or characteristic. There are seven such prefixes, these are:


1) Prefix “un-”
The examples can be the following: “un + necessary = unnecessary; un + clear = unclear; un + friendly = unfriendly (* Note down, that “friendly” is still an adjective, do not confuse it with an adverb, unless it has the suffix “-ly”)”.

2) Prefix “dis-”
The examples of this prefix are: “dis + respectful = disrespectful; dis + honest = dishonest; dis + similar = dissimilar”. Pay attention to the word “dissimilar”, do not be confused because of its spelling, there is a doubled “s” and it is okay.

3) Prefix “non-”
Let us draw some examples: “non + essential = nonessential; non + functional = nonfunctuanal; non + poisonous = nonpoisonous”.

4) Prefix “im-”
This prefix should be used with the adjective that starts with the letters “m” or “p”. For instance: “im + mortal = immortal; im + possible = impossible”.

5) Prefix “ir-”
Such a prefix is used with adjectives that start with the letter “r”. For instance: “ir + responsible = irresponsible; ir + regular = irregular”.

6) Prefix “il-”
Use the prefix “il-” with adjectives that start with “l”, like: “ il + legal = illegal; il + licit = illicit”.

7) Prefix “in-”
This suffix is not used after some exact letters, it’s usage is not similar to suffixes “il-, ir-, im-”. But, in common, it goes before “ac-” and the letters “c/s”. The examples can be the following: “in + secure = insecure; in + active = inactive”.


To sum up, we have learned seven English prefixes with the meaning of lack or negation. They are used with non-compound adjectives. Use those prefixes to improve your communication skills and boost your vocabulary!