Prefix: un-
Source: DfE, English Appendix 1: Spelling (2013) — Year 1 and Year 2 statutory prefix
Origin: Old English un-, meaning "not" or "reverse of"
Purpose: Guide to the prefix un- for KS1 and KS2 — meaning 'not' or 'reversal', word list with definitions, and morpheme-based practice activities.
What it means
un- has two meanings:
- Not: unhappy = not happy, unkind = not kind
- Reverse of: unlock = reverse of locking, undo = reverse of doing
Where it comes from
un- is one of the oldest prefixes in English, descended directly from Old English (before 1066). Unlike most prefixes which came with the Normans from Latin and French, un- is pure Old English — which is why it sounds natural and informal. It's been part of English for over 1,500 years.
Statutory examples by year group
Year 1 (statutory): unhappy · undo · unfair · unlock · unwell · untie · unlike
Year 2 (statutory extension): unusual · unsafe · unable · unpack · unclear · unfit · unusual
Year 3/4 (consolidated): unnatural · unnecessary · unusual · uncertain · unfamiliar
Morpheme matrix
| un- | (nothing) | |
|---|---|---|
| -happy | unhappy | happy |
| -kind | unkind | kind |
| -do | undo | do |
| -lock | unlock | lock |
| -fair | unfair | fair |
| -safe | unsafe | safe |
| -well | unwell | well |
| -usual | unusual | usual |
| -able | unable | able |
| -natural | unnatural | natural |
The double n cases
When un- is added to a word starting with n, you get two ns. This is correct and follows the rule (prefix added intact, base word unchanged):
- un- + natural = unnatural
- un- + necessary = unnecessary
- un- + noticed = unnoticed
- un- + named = unnamed
Children often write unatural — remind them: the prefix un- is always spelled un-, and natural is always spelled natural. Put them together: un + natural = unnatural.
un- vs dis- vs in-
All three can mean "not," but they attach to different words:
| Prefix | Typical use | Example |
|---|---|---|
| un- | Old English base words | unhappy, unkind, unwell |
| dis- | Latin/French base words | disagree, disappear, dishonest |
| in- | Latin adjectives | impossible, incorrect, inactive |
un- sounds native and informal. dis- and in- sound more formal. Same meaning, different register.
Dictation sentences
- She was unhappy when she found the door unlocked and the room in an untidy state.
- It was unsafe and unwise to cross the unlit road at night.
- The unusual creature was unlike anything anyone had ever seen before.
- The unnecessary delay meant the unfinished work could not be undone.
- Unable to continue, she sat down and waited until the storm passed.
Source: DfE English Appendix 1: Spelling (2013). Etymology: Old English un-, cognate with Latin in- and Greek a-/an-.