Type of prefix: adjectival, adverbial, nominal
The French prefix in is added to many adjectives as well as some adverbs and nouns to create their opposites. In is usually equivalent to the English prefixes "un" or "in."
inacceptable - unacceptable
(added to acceptable - acceptable)
inachèvement - incompletion
(added to achèvement - completion)
indécemment - indecently
(added to décemment - decently)
inconscient - unconscious
(added to conscient - conscious)
In- and its variants
As shown in the above examples, the prefix in- is the most common spelling; it's added to words that begin with a vowel or a consonant other than b, l, m, p, or r.
Im- is used with words that begin with b, m, or p:
imbrûlé - unburnt
(added to brûlé - burnt)
immature - immature
(added to mature - mature)
impartialité - impartiality
(added to partialité - bias)
Il- is needed for words that begin with l:
illégal - illegal
(added to légal - legal)
illisible - illegible
(added to lisible - legible)
Ir- is added to words that begin with r:
irrationnel - irrational
(added to rationnel - rational)
irrégulier - irregular
(added to régulier - regular)
The pronunciation of in and its variants can be a little tricky:
- In is pronounced [een] in front of a vowel or the letter n. In front of other consonants, in is pronounced [eh(n)].
- Im is pronounced [eh(n)] in front of b or p, and in a few other words (immangeable, immanquable, immariable, immettable).
Otherwise, it's pronounced [eem]: immense, immatériel, immature, etc.
- The prefix il is pronounced [eel]
- The prefix ir is pronounced [eer]
Related lessons: French negation