You have come across words such as illegal, inadequate, irresponsible and immoral?
The il- in- ir- and im- mean the same: ‘not’ or ‘the opposite of’. That implies that words that begin with one of the four carry the element of negation or opposite of the rest of the word.
You may ask why there are such four prefixes with the same meaning instead of one. The reason is in English language spelling rules (orthography) where letters at the beginning of a word determines what letters should come before them and so what prefix is fit. For example the word ‘moral’ cannot take ir- for its opposite to be ‘Irmoral’.
If you know that the word ‘inadequate’ means ‘not enough’ or the opposite of being adequate, then you should be aware that the word ‘illegal’ means ‘not legal’ or the opposite of being legal (lawful/ allowed according to the law).
‘Illegible’ means not legible or ‘unreadable’ and ‘illiterate’ means ‘not literate’ or not able to read and write.
You will have to apply the same rule for similar words like impossible, impure, incapable, incomplete, indefinite, irregular, irresistible, irrational and many more.
However, you must have come across words that begin with one of the four prefixes especially in- and im- in senses that do not mean ‘not’ or ‘the opposite of’. Examples include import, impose, implore, implant, inbox, inbreed, inflict, insert, inside and many more.
This is the other element of word that begin with in- and im- which largely means ‘into’.
A word such as ‘import’ comes from ‘in port’ which commercially means bringing goods and services into a country from abroad.
By understanding the prefix in- you can be able to differentiate words such as inflict from afflict.
First the word ‘flict’ is Latin origin meaning ‘to strike’. Therefore inflict and afflict mean causing pain but by to inflict means to force pain or sufferinginto something or someone.
If a word that begin with ir-, il- im- or in- does not fit in the first context of ‘not’, try looking at it in the context of ‘into’.
The writer is a professional English Language instructor