Websink Prep UKKS2 EnglishYear 5 chaptersEnglish textbooksReceptionYear 1Year 2Year 3Year 4Year 5Year 6Year 7Year 8Year 9Browse allPast papersFind a tutorBecome a tutor
Primary English · Year 5Chapter 2 · Prefixes: in-, dis-, de-, re-, auto- and bi-
Year 5 English · Prefixes: in-, dis-, de-, re-, auto- and bi- · Lesson 2.1

Year 5 English: Prefixes that mean not: in-, il-, im- and ir-

Part of the Year 5 English prefixes: in-, dis-, de-, re-, auto- and bi- chapter. Chapter overview · whole chapter on one page

2.1

Prefixes that mean not: in-, il-, im- and ir-

Year 5
Spell and use prefixes in-, il-, im- and ir- that mean not (SP-Y5e)
Story. Ravi is writing the rules for a club. One rule says that a member must not be inactive for a month. Another says that a payment that is incorrect or illegal must be reported. He notices that the prefix changes before different letters.

Key pattern

Several prefixes mean not. The prefix in- is used before most letters: active becomes inactive.

Before l, the prefix becomes il-: legal becomes illegal.

Before m, p or b, the prefix becomes im-: mature becomes immature; patient becomes impatient.

Before r, the prefix becomes ir-: regular becomes irregular.

Key ideas

  • in- means not, and it is used before most letters: incorrect, inactive.
  • il- is used before l: illegal, illogical.
  • im- is used before m, p and b: immature, impatient, imbalance.
  • ir- is used before r: irregular, irrelevant.
Worked example 2.1.1
Add a prefix to logical to make a word that means not logical.

Method. The root word starts with l, so the prefix is il-.

  1. Find the first letter of the root. Logical starts with the letter l.
    logical
  2. Choose the prefix. Before l, the prefix is il-.
    il + logical
  3. Write the answer.
    illogical

Check. Illogical means not logical. ✓

Worked example 2.1.2
Add a prefix to patient to make a word that means not patient.

Method. The root word starts with p, so the prefix is im-.

  1. Find the first letter of the root. Patient starts with the letter p.
    patient
  2. Choose the prefix. Before p, the prefix is im-.
    im + patient
  3. Write the answer.
    impatient

Check. Impatient means not patient. ✓

Worked example 2.1.3
Which word means not regular: irregular or inregular?

Method. The root word starts with r, so the prefix is ir-.

  1. Find the first letter of the root. Regular starts with r.
    regular
  2. Choose the prefix. Before r, the prefix is ir-.
    ir + regular
  3. Write the answer.
    irregular

Check. Irregular is correct. ✓

Exercise 2A  Practice: prefixes that mean not

1
FAdd a prefix to correct to make a word that means not correct.
2
FAdd a prefix to complete.
3
FAdd a prefix to active.
4
FAdd a prefix to legal.
5
FAdd a prefix to logical.
6
FAdd a prefix to patient.
7
FAdd a prefix to mature.
8
FAdd a prefix to balance.
9
FAdd a prefix to regular.
10
FAdd a prefix to relevant.
11
PSAli says inlegal is right. Write the correct spelling.
12
RExplain why impossible uses im- and illegal uses il-.

Websink Prep UK is an independent site. It is not affiliated with, endorsed by or sponsored by AQA, Pearson Edexcel, OCR, WJEC, Eduqas, CCEA, SQA, GL Assessment, CEM or the Department for Education. All exam board names and trademarks belong to their owners. Past papers are linked from the exam boards' own websites and are not hosted here.

About Websink Prep UK · Find a tutor · Privacy · Terms · Cookie settings