Use the Prefixes im-, il-, ir- and in-

A prefix is a letter or group of letters added to the beginning of a word to change the meaning.

Knowing what a prefix means can help us to understand new words.

 

In this activity, we’re going to look at prefixes which give the root word the opposite meaning.

These prefixes turn root words into their antonyms (opposites):

 

The Prefix im-

What is the opposite (antonym) of the word possible?

If something isn’t possible, it’s impossible.

 

For words beginning with the letter p or the letter m, we use the prefix im- to create an antonym.

 

Word	Antonym
possible	impossible
mobile	immobile
mature	immature

 

 

Where the root word began with m, we end up with an antonym with a double m.

 

Can you think of any other words with the prefix im-?

 

The prefix il-

What is the opposite of the word legal?

If something isn’t legal, it’s illegal.

 

For words beginning with the letter l, we use the prefix il- to create an antonym.

 

Word	Antonym
legal	illegal
logical	illogical

 

 

This prefix creates words with a double l.

 

The Prefix ir-

We use the prefix ir- to create an antonym for root words beginning with r.

 

Word	Antonym
reversible	irreversible
resistible	irresistible

 

 

The Prefix in-

If a root word doesn’t begin with a m, p, r or l, we use the prefix in- to create an antonym.

 

Word	Antonym
appropriate	inappropriate
complete	incomplete

 

All of these prefixes mean not and give words the opposite meaning.

 

In this activity, you will use your knowledge of these prefixes to answer word-meaning and spelling questions.