Prefixes and Suffixes — English Bac Lettres

Dans le programme du Bac Lettres

English is a major subject in the Bac Lettres stream, with a coefficient of 4 — second only to Arabic Language (coefficient 7) and ahead of History-Geography and Philosophy (coefficient 3). There is no Mathematics in the stream. The high coefficient raises the bar: richer vocabulary, more developed argumentative writing, and firmer control of register and style are expected, and the English mark genuinely shapes the average.

À l'épreuve

Three parts: Reading Comprehension, Language, and Writing. In the Lettres stream the Writing task is longer and more demanding — a structured essay with a clear thesis, developed arguments on both sides, illustrative examples and a personal conclusion — and language accuracy and range are scored throughout.

Objectifs d'apprentissage

Reuse this vocabulary field in the Bac Lettres Reading answers and in the argumentative essay (coefficient 4)
Recognise the most common negative prefixes: un-, dis-, im-, in-, ir-, il-, non-
Form a noun from an adjective or a verb with suffixes (-ness, -ity, -tion, -ment)
Form an adjective from a noun or a verb with suffixes (-ful, -less, -able, -ive)
Form an adverb of manner by adding -ly to an adjective

Notions clés

Negative prefixes

un- (happy → unhappy), dis- (agree → disagree), im- (before b / m / p: possible → impossible), in- (correct → incorrect), ir- (before r: responsible → irresponsible), il- (before l: legal → illegal). The choice often depends on the first letter of the base word.

Noun suffixes

-ness (happy → happiness), -ity (able → ability), -tion / -sion (educate → education, decide → decision), -ment (develop → development) — they turn an adjective or a verb into an abstract noun.

Adjective and adverb suffixes

-ful (help → helpful), -less (hope → hopeless, opposite of -ful), -able / -ible (accept → acceptable), -ive (create → creative) for adjectives; -ly added to an adjective for the adverb of manner (quick → quickly, happy → happily with y → i).

Erreurs fréquentes

Using the wrong negative prefix by false analogy: “inresponsible” is wrong — use irresponsible (ir- before r).

Confusing -ful and -less, which have opposite meanings: hopeful (full of hope) vs hopeless (without hope) — one letter changes the whole meaning.

Forming an irregular adverb as if it followed the general rule: good → goodly does not exist; the correct adverb is well.

Exemple corrigé

Énoncé

Complete with the correct form of the word in brackets: “Her decision to leave the company was completely ___ (understand).”

Correction

Identify the grammatical function needed. After “completely”, an adverb is possible, but here the structure “was completely ___” calls for an adjective after the verb be.

Choose the right suffix. understand (verb) → understandable (adjective, with the suffix -able).

Result. “Her decision to leave the company was completely understandable.”

Le cours, puis l'entraînement.

Orka génère des exercices illimités et des examens blancs corrigés sur tout le programme de Anglais du Bac Lettres, avec un suivi de ta progression chapitre par chapitre.

Continue gratuitement sur Orka

3 exercices pour t'entraîner

Exercice 1

Easy

Form the noun from happy: happy → ___

Voir la correction

happiness — the suffix -ness turns an adjective into an abstract noun.

Exercice 2

Medium

Choose the right negative prefix: ___legal, ___possible, ___correct

Voir la correction

illegal (il- before l), impossible (im- before p), incorrect (in-, the general case).

Exercice 3

Hard

Complete with the correct form: “The company's new policy was met with widespread ___ (approve) among employees.” (mind the negative meaning called for by “widespread ___”)

Voir la correction

disapproval — the prefix dis- reverses the meaning of approve to disapprove, then the suffix -al forms the noun; the context (a badly received policy) confirms the negative meaning.

Va plus loin sur ce chapitre

50+ exercices interactifs sur ce chapitre

Générés et corrigés étape par étape par l’IA, à ton niveau.

Connexion requise

Quiz IA adaptatif

Questions qui s’ajustent automatiquement à tes réussites et erreurs.

Connexion requise

Corrigés d’annales sur ce chapitre

Sujets d’examens nationaux et régionaux déjà tombés.

Connexion requise

Plan de révision personnalisé

Priorise ce chapitre selon ta progression réelle sur toute la filière.

Premium

Flashcards du chapitre

Formules et définitions clés en mode révision rapide.

Premium

Tuteur IA en Darija

Pose tes questions sur ce chapitre et obtiens une explication immédiate.

Premium

Questions fréquentes

How do I guess the meaning of an unknown word from prefixes / suffixes in the exam?

Spot the known root (for example “legal” in illegal), then identify the prefix (il- = negation) or the suffix (-tion = noun) to work out the meaning and the word class, even without knowing the word.

Is there a single rule for choosing between un-, in-, im-, il-, ir-?

No absolute rule, but a useful tendency: ir- before r, il- before l, im- before b / m / p, in- otherwise, and un- with many Anglo-Saxon adjectives (happy, fair, kind) rather than Latin ones.

Do -ful and -less apply to every noun?

No, they are productive but not universal: some pairs exist (hope / hopeful / hopeless, care / careful / careless) while other words have only one usual form — when in doubt, check rather than guess in the exam.

English is coefficient 4 in the Lettres stream — how do I revise it seriously?

Treat it as a core subject. For each of the 31 chapters, fix the rule or the word field with two solid examples, and write at least one full essay a fortnight under timed conditions. Read short English articles to build argumentative vocabulary and sentence variety, since range and accuracy are marked directly.

How do I use this theme in the Bac Lettres essay without sounding generic?

Anchor each key term in one concrete, personal example — a place, a person, a situation you know. A specific illustration in accurate English scores better than a long list of terms with no support, on any of the society prompts in the programme.