Meaning & use
the prefix a-
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Meanings
prefix
A prefix meaning 'not' or 'without', added to adjectives and nouns (e.g., atypical, asymmetry).
Grammar: It attaches to the front of a word; the resulting word often has the same part of speech as the base.
Patterns
- a- + adjective
- a- + noun
An atypical reaction is one that is not typical.
Asymmetry means a lack of symmetry.
The patient showed atypical symptoms, so the doctor ordered more tests.
prefix
A prefix meaning 'in' or 'on', showing a state or position (e.g., asleep, aboard, afire).
Grammar: It often forms adjectives or adverbs that describe a temporary state, not a permanent quality.
Patterns
- a- + noun
- a- + verb participle
The baby is asleep in the next room.
The sailors went aboard the ship.
The house was afire before the firefighters arrived.
prefix
A prefix meaning 'on' or 'in' in words like 'aboard' and 'afoot'.
Grammar: This sense is less common and appears in fixed words; it is not a general rule for forming new words.
Patterns
- a- + noun
There is a plan afoot to change the schedule.
The crew is aboard the plane.
Common combinations
- atypical
- His behavior was atypical for someone so young.
- asleep
- She fell asleep during the movie.
- aboard
- All passengers are now aboard.
- asymmetry
- The asymmetry of the design was intentional.
Commonly confused: the prefix a- or a (article)?
the prefix a- vs a (article)
The indefinite article 'a' is a separate word, not a prefix. 'Atypical' has the prefix 'a-' meaning 'not', while 'a typical day' uses the article 'a'.
Practice
What does the prefix 'a-' mean in the word 'atypical'?
Choose one answer.
In 'atypical', 'a-' means 'not', so 'atypical' means 'not typical'. The other options are possible meanings of 'a-' in other words, but not here.
Make it your own
Write a sentence using “the prefix a-”, then check it and compare it with the examples above.